You simply cross multiply
36/32 = n/64
becomes
(36)(64)/32 = n
n = 72
These are ratios. You are going to see a lot of them. sometimes the variable will be on the bottom. In which case you still cross multiply, but then you will have to divide whatever the coefficient of the variable is. For example, if you have
4/5 = 3/n
you would get
4n = (3)(5)
4n=15
n = 15/4
