Question

Assume y varies directly as x. If y = 30 when x = -3, find y when x = -9.

Answer 1

y is 90

Explanation:

The y/x is proportional per point (x,y) since this is a direct variation.

That is ,

`(30)/(-3)=(y)/(-9)`.

Cross multiply:

`30(-9)=y(-3)`

Simplify:

`-270=-3y`

Divide both sides by -3

`(-270)/(-3)=y`

`90=y`