OH you have to find what the lengths of the sides of the squares are, It would have been easier if they made the area 36 because that is a squared number and easy to find but because they didn't you just have to put 32 into a square root and the output would be 5.6.
why are we doing this? because 5.6*5.6=32, the area of the square. that means that 5.6 and 5.6 can be plugged into the A^2+B^2=C^2 equation 5.6^2+5.6^2=c^2 the missing side.
=984 should be the missing side but do the work yourself because that number that I came up with doesn't look right.