Question

If these two figures are similar what is the measure of the missing side length J?

Answer 1

If the long side on both is 9ft and 3ft then 3•3 is 9 so for the short side you do the same. If the short side is 1ft and the other is "j" then it's 1•3 is 3.

1•3=3
Sorry if it's confusing the way I explained it.