Think of the "how much" as the variable let's call it x, "is" means = and "of" means times.
x= 1/3 × 36 (since 36 is not a fraction make it one by putting it over 1)
x= 1/3 × 36/1 (remember to multiply you multiply straight across)
1×36=36 & 3×1=3
36/3 then divide to get 12.