Write a direct variation equation that relates x and y. Assume that y varies directly as x. Then solve.

If y = –5 when x = 15, find y when x = –1.

Question

Write a direct variation equation that relates x and y. Assume that y varies directly as x. Then solve.

If y = –5 when x = 15, find y when x = –1.

anonymous · Answer

a. y=-1/5x;1/5
b. y=-1/3x;2/5
c. y=1/3x;-1/3
d. y=-1/3x;1/3

e.mccormick · Answer

Which part are you getting stuck on?

anonymous · Answer

how to do it

e.mccormick · Answer

Direct variation means there is some sort of ratio between the values, and it is always the same ratio.  So, they start with $y=-5$ and $x=15$.  Do you see a ratio between those numbers?