one way to solve this is to set up a proportion:
some number compared to 100 is equal to 12 compared to 72.
The proportion looks like this:
[tex] \frac{x}{100} = \frac{12}{72} [/tex]
solving for x we get 16.6666666 repeating which is 16[tex] \frac{2}{3} [/tex]%
