Y varies inversely as x and y=5 when x=3

Xy=k

3*5=k

k=15

xy=15 or y=15/x

So if somthing varies inversely then when one value goes up, the other value goes down so xy=z and z has to be the same so lets say that z=16

when x=2 y=8

when x=4 y=4

when x=8 y=2

when x=16 y=1

so xy=z

subtitute

(3) (5) = 15

so if x=5 y=3

x=1 y=15

x=15 y=1