the value of y varies directly with x and y=-1 when x=3, find y if x=9

Answer 1

x : 3 :: y : -1

9 : 3 :: y : -1

3y = -9

y = -3

Answer 2

y varies directly with x.

When x = 3, y=-1

This indicates that y = -1/3 * x

So if x = 9 and y = -1/3 * x, then y = -1/3 * 9 = -9/3 = -3