please help!

Question

y varies inversely as x and y = -40 when x =13, find y if x = 7

Answer 1

y varies nversely x

y = k/x

xy = k

Given x = 13 and y = -40

 13*-40 = k

k = -520

Now x = 7 and y = ?

xy = k

7*y = -520

y = -520/7

y = 74.28