Question

If y= 12 when x= -15, find y when x= 2

Answer 1

y = 12 when x = -15

Direct variation equation is y = kx.

The given numbers form one ratio expressed as y/x = 12/-15

To find y, when x = 2

we set up another ratio y/2

By the definition both ratios are equal 12/-15 = y/2

Multiple to each side by 2.

12*2/-15 = 2y/2

8/-5 = y

y = -8/5