Question

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

Answer 1

Answer:

y is 90

Step-by-step explanation:

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

That is ,

$\frac{30}{-3}=\frac{y}{-9}$.

Cross multiply:

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

Simplify:

$-270=-3y$

Divide both sides by -3

$\frac{-270}{-3}=y$

$90=y$