36 is what % of 720

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