Question

y varies inversely with x. When x is 5, y is 4. What is the constant of inverse variation, k?

Answer 1

K = XY
K = 5*4
K = 20

When y inversely varies with x, the equaiton is k = xy.  Plug in your constants of 5 for x and 4 for y, and you get your constant of variation as 20.