Question

The value of y varies directly with x, and y = 40 when x = -5. Find y when x = 8

Answer 1

Answer: y=-64

Explanation:

From the first sentence: the value of y varies directly with x:

y∝x

y=cx where c=variation constant

When y=40 x=-5

40=-5c

Therefore c=-8

To find y when x=8

y=cx where c=-8 and x=8

y=-8*8

y=-64