Question

A rectangle has an area of 36 inches squared. Write an equation to show how the length (l) varies inversely the width (w).

Answer 1

Start with the first sentence, and the definition of the area of a rectangle:
l * w = 36

Rewrite the equation to get
l = 36 / w
or
w = 36 / l
Either one shows the inverse relationship between w and l.

Assuming the last part wants you to write an equation for an x-y graph, the equation would be
y = 36 / x