1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Aleks04 [339]
3 years ago
8

The sum of two numbers is 21,and their difference is 9

Mathematics
2 answers:
Nimfa-mama [501]3 years ago
8 0

Answer:

The numbers are 15 and 6.

Step-by-step explanation:

We can solve the problem algebraically (using equations). First, write equations that represent the situation.

Choose variables to represent the numbers:

let the numbers be "x" and "y"

Take apart each section of the problem and make an equation.

"The sum of two numbers is 21"

x + y = 21             Sum means the answer when you add numbers

"Their difference is 9"

x - y = 9               Difference means the answer when you subtract numbers

Using the two equations, you can solve using <u>elimination</u>. With this method, you get rid of one of the variables, so you can easily solve for the other one. You can use elimination when one of your variables have the same variable number. Both equations have "1x" and "1y" ("1" is never written).

Add the equations together by adding normally, with each of the terms with the same variable.

.     x + y = 21             Add each term

<u>+     x - y = 9</u>            (x + x = 2x)     (y + (-y) = 0)     (21 + 9 = 30)

.   2x + 0 = 30         "y" variable cancelled out

.          2x = 30        

.       2x/2 = 30/2         Divide both sides by "2" to isolate "x"

.            x = 15         Answer for one number

To find the other number, substitute 'x' for 15 into one of the equations.

x + y = 21

15 + y = 21         Isolate "y" now

15 - 15 + y = 21 - 15         Subtract 15 from both sides

y = 21 - 15         15-15 cancelled out on the left side. Solve right side.

y = 6       Answer for second number

Therefore the two numbers are 15 and 6.

Ghella [55]3 years ago
3 0
let's say the two numbers are x and x + 9. so we know x + x + 9 = 21, so 2x + 9 = 21. subtract 9 from both dies to get 12 = 2x. divide both sides by 2 to get x = 6. so your two numbers are 6 and 15.
You might be interested in
What is the value of k in the equation below
Dima020 [189]

Answer:

<h2>4</h2>

Step-by-step explanation:

5k-2k=12

3k=12

k=4

5 0
3 years ago
Does anybbody know the answer to this? #help
Gwar [14]

Answer:

each tube costs $1.5 so put it the point in between 1 and 2

thank you

Step-by-step explanation:

5 0
2 years ago
Does anyone know the answer
maria [59]
#5 is 1845 and #6 should b 4
4 0
3 years ago
rick jogged the same distance on tuesday snd friday, and 8 miles on sunday for a total of 20 miles for the week. solve to find t
saveliy_v [14]

Ricky jogged 6 miles on tuesday and 6 miles on friday

<em><u>Solution:</u></em>

Given that,

Rick jogged the same distance on tuesday and friday

Let "x" be the distance jooged on each tuesday and friday

He also jogged for 8 miles on sunday

Total of 20 miles for the week

Therefore, we frame a equation as,

total distance jogged = miles jogged on tuesday + miles jogged on friday + miles jogged on sunday

20 = x + x + 8

20 = 2x + 8

2x = 20 - 8

2x = 12

x = 6

Thus Ricky jogged 6 miles on tuesday and 6 miles on friday

3 0
3 years ago
Which of the following is solution to the compound inequality below?
djverab [1.8K]
Solve compound inequalities<span> in the form of or and express the </span>solution<span> graphically. ... determining the</span>solution to the compound inequality<span>, as in the example </span>below<span>. .... </span>Which of the following compound inequalities<span> represents the graph 

</span>
4 0
3 years ago
Read 2 more answers
Other questions:
  • Reggie earns $12.65 per hour and works 38 hours per week. How much does he warm in a week before taxes are taken out?
    13·1 answer
  • Draw quick picture and write to explain how to break addends to find the sum of 324+231
    11·1 answer
  • In a survey of 800 students,
    10·1 answer
  • PLEASE HELP ASAP
    14·1 answer
  • The distributions of heights of 1000 men and 1000 women selected at random from the population of a large metropolitan area are
    12·1 answer
  • Is it easier to find the x-intercept of the graph of the equations using slope-intercept or standard form? Explain.
    10·1 answer
  • An actor was paid $2.1 x 10^6 (this an exponent) to star in a movie. If the
    5·1 answer
  • 4. A 12,000 kg truck is traveling down the road when it slams on its breaks. It travels 70 m before it slows to a
    12·1 answer
  • Answer these 3 questions ASAP pls..
    14·1 answer
  • Fire Fighters are attempting to rescue people from the 3rd floor of a building. The
    8·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!