Question

Suppose that y varies directly with x

and y=
= 10 when x = 20. What is y
when x = 15?
Be sure to simplify your answer.

Answer 1

y = 7.5

Explanation:

Given y varies directly with x then the equation relating them is

y = kx ← k is the constant of variation

To find k use the condition y = 10 when x = 20

10 = 20k ( divide both sides by 20 )

`(1)/(2)` = k

y =
`(1)/(2)` x ← equation of variation

When x = 15 , then

y =
`(1)/(2)` × 15 =
`(15)/(2)` = 7.5

Answer 2

`10 * 2 = 20 \\ 5 * 3 = 15`

answer:10×2=20

5×3=15