You would set up this problem as:
36=x * 720
divide 36 by 720:
x= $${\frac{{\mathtt{36}}}{{\mathtt{720}}}} = {\frac{{\mathtt{1}}}{{\mathtt{20}}}} = {\mathtt{0.05}}$$
Convert the decimal answer 0.05 to percent by multiplying it by 100.
x = 0.05 * 100
= 5 percent