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
ra1l [238]
2 years ago
12

The ratio of Wei Ling's age to Wei Xuan's age 5 years ago was 2: 5. In 9 years

Mathematics
1 answer:
Archy [21]2 years ago
6 0

Answer:

15 years old

Step-by-step explanation:

Start by defining the variables that we are going to use throughout our working:

Let the current age of Wei Ling and Wei Xuan be L and X years old respectively.

Next, form equations using the given information.

<u>5 years </u><u>ago</u>

Wei Ling: (L -5) years old

Wei Xuan: (X -5) years old

Given that the ratio of Wei Ling's age to that of Wei Xuan's is 2: 5,

\frac{ L - 5}{X - 5}  =  \frac{2}{5}

Cross multiply:

2(X -5)= 5(L -5)

Expand:

2X -10= 5L -25

2X= 5L -25 +10

2X= 5L -15 -----(1)

<u>9 years time</u>

Wei Ling: (L +9) years old

Wei Xuan: (X +9) years old

Given that the ratio of Wei Ling's age to that of Wei Xuan is 3: 4,

\frac{L + 9}{X + 9}  =  \frac{3}{4}

Cross multiply:

3(X +9)= 4(L +9)

Expand:

3X +27= 4L +36

3X= 4L +36 -27

3X= 4L +9 -----(2)

Let's solve using the elimination method.

(1) ×3:

6X= 15L -45 -----(3)

(2) ×2:

6X= 8L +18 -----(4)

(3) -(4):

6X -6X= 15L -45 -(8L +18)

0= 15L -45 -8L -18

0= 7L -63

7L= 63

L= 63 ÷7

L= 9

Substitute L= 9 into (1):

2X= 5(9) -15

2X= 45 -15

2X= 30

X= 30 ÷2

X= 15

Thus, Wei Xuan is 15 years old now.

You might be interested in
What is a simple way to tell that -31 is not the slope of this graph?
Trava [24]

The change in x from A to B is positive. The line is going up, so the slope cannot be negative

:)

7 0
2 years ago
Find f(-3) if f(x) = x2<br> Help me please!!
tatuchka [14]

Answer:

-3x^2

Step-by-step explanation:

negative three x squared

4 0
3 years ago
Suppose total benefits and total costs are given by b(y) = 100y − 8y2 and c(y) = 10y2. what is the maximum level of net benefits
olga nikolaevna [1]
Whenever you face the problem that deals with maxima or minima you should keep in mind that minima/maxima of a function is always a point where it's derivative is equal to zero.
To solve your problem we first need to find an equation of net benefits. Net benefits are expressed as a difference between total benefits and total cost. We can denote this function with B(y).

B(y)=b-c
B(y)=100y-18y²

Now that we have a net benefits function we need find it's derivate with respect to y.

\frac{dB(y)}{dy} =100-36y

Now we must find at which point this function is equal to zero.

0=100-36y
36y=100
y=2.8

Now that we know at which point our function reaches maxima we just plug that number back into our equation for net benefits and we get our answer.

B(2.8)=100(2.8)-18(2.8)²=138.88≈139.

One thing that always helps is to have your function graphed. It will give you a good insight into how your function behaves and allow you to identify minima/maxima points.


3 0
2 years ago
Write the equation of the circle with a center at (11,6) and a radius of 6.
andrew11 [14]

Answer:

(x-11)^2 + (y-6)^2= 6^2

Step-by-step explanation:

3 0
3 years ago
Read 2 more answers
55 is 40% of what number
SCORPION-xisa [38]
You simply put 40 over a hundred and 55 over n (which is the number were trying to find)  so you do cross multiplication. 55 times a hundred and after you get the answer. You divide it by 40 and should get 137.5.
3 0
3 years ago
Other questions:
  • Factor the polynomial.
    13·1 answer
  • If the perimeter of an equilateral triangle is 30 ft, what is the area?
    15·1 answer
  • What is 10 times 2 divided by 4 plus 3
    10·2 answers
  • 10 students are standing equidistant from the center of a classroom. they are all holding hands to begin with. they must go and
    10·2 answers
  • Solve the simultaneous equations<br>2x + 5y + 11 = 0<br>3x - y-8= 0​
    9·1 answer
  • 21 = -4x - 7<br> What is the answer
    5·1 answer
  • Donna wants to save $700 to buy a TV. She saves $17 cach week. The amount, A (in dollars), that she still needs after w weeks is
    8·1 answer
  • Write each fraction number as a decimal write each fraction number as a decimal 4/33
    10·1 answer
  • What is the equation of the line?<br> I’LL GIVE BRAINLIEST
    13·2 answers
  • Two students are registered for the same class and attend independently of each other, student a 90% of the time and student b 7
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!