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
Ronch [10]
3 years ago
15

John is twice as old as Mary. The sum of thelr ages is 21. How old Is Mary?

Mathematics
2 answers:
Cerrena [4.2K]3 years ago
7 0

Answer:

Step-by-step explanation:

Let Mary's age = x years

John's age = 2 * x = 2x

The sum of their ages = 21

x + 2x = 21

3x = 21

Divide both sides by 3

x = 21/3

x = 7

Mary's age = 7 years

Kaylis [27]3 years ago
5 0

Answer:   7 years

Step-by-step explanation:

let x be the age of Mary

so John's age will be 2x

the equation becomes

2x+x=21

3x=21

x=21/3

x=7

You might be interested in
Explain, using complete sentences, the Transitive Property of Equality in geometric terms.
MariettaO [177]

Answer:

Transitive Property of Equality. The following property: If a = b and b = c, then a = c. One of the equivalence properties of equality. Note: This is a property of equality and inequalities. (Click here for the full version of the transitive property of inequalities.)

<h2>Please mark me as brainlyist quick</h2>

6 0
3 years ago
Which experimental design compares two groups (randomly formed) on the same task, such as movement speed
anygoal [31]

Between-group design compares two groups (randomly formed) on the same task, such as movement speed.

Given things that there are two groups that are randomly formed for the same task.

A between-group design in experimental design is an experiment in which two or more groups of individuals are assessed simultaneously by separate testing factors. This design is typically used instead of, or in conjunction with, the within-subject design, which applies identical modifications of circumstances to each participant in order to monitor the reactions.

Learn more about experimental designs at brainly.com/question/17280313

#SPJ4

3 0
2 years ago
The equation V equals pi r squared h, where r represents radius and h represents height, is used to find the volume of a _______
baherus [9]

Answer:

Volume of a cylinder.

Step-by-step explanation:

The given equation is :

V=\pi r^2 h

Where

r is the radius

h is the height

This equation is used to find the volume of a cylinder.

For example, a cylinder having radius of 7 units and height of 10 units, its volume will be :

V=\dfrac{22}{7}\times 7^2\times 10\\\\V=1540\ \text{unit}^2

So, the given equation is used to find the volume of a cylinder.

7 0
3 years ago
Please help me, and I will mark you as brainliest
Lostsunrise [7]

Answer:

what is the equation that u actually looking for?

Step-by-step explanation:

6 0
2 years ago
Read 2 more answers
Graph the Rarabola.---Plot five points on the parabola: the vertex, two points to the left of the vertex, and tvbutton2Explanati
valentinak56 [21]

Which parabola?

y=-x^2

Equation of the parabola

y - y1 = 4p(x - x1)

The Vertex of the parabola given is (0, 0) because it does not have the values of x1 and y1.

Then Vertex = (0,0)

-Look for two values of y to the left and two points to the right.

You can choose the points that you which

x y

-3 y = -(-3)^2 = -9

-1 y = -(-1)^2 = -1

0 y = -(0)^2 = 0

1 y = -(1)^2 = -1

3 y = -(3)^2 = -9

3 0
1 year ago
Other questions:
  • Write the equation of a line in slope intercept form if the slope is 9 and a Y intercept is 13
    9·1 answer
  • Generate the first five terms in the sequence using the explicit formula. cn= 12n - 11
    15·1 answer
  • The Soup Shack usually makes tomato soup with 9 tomatoes for every 12 cups of soup. Today, they made 8 cups of soup with 6 tomat
    6·1 answer
  • As part of survery , 300 girls were asked to name their favorite sport . the results showed that 12 of the girls named bowling a
    15·1 answer
  • Hailey has 9 Spirit wear tops and 4 pairs of jeans. How many ways can she pair a top with a pair of jeans?
    6·1 answer
  • The data set represents the number of minutes Dan spent on his homework each night.
    15·2 answers
  • Point B is located between points A and C, AB= X^2-10, BC= 2X +2 and AC= 16 ,solve for X
    13·1 answer
  • Joesph and molly each have coin collections. Joesph starts with 15 coins in his collection and adds 25 coins each month. Molly s
    6·1 answer
  • Help me plssss pretty pls
    11·2 answers
  • Can someone answer this question please
    8·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!