Question

16 is 20% of what number?

Answer 1

80 because 16 divided by 20%
of means multiply but in this case divide

Answer 2

Set up a proportion first using this formula: 
number/100 = is/of (they are set up like fractions) 

Plug corresponding values into equation: 
20/100 = 16/x (or whatever variable you choose) 

Cross multiply the values: 
20 * x and 100 *16

Set the resulting products equal to each other: 
20x=1600

Isolate the variable by dividing the value in front of it by both sides: 
20x/20 and 1600/20 

Set the variable equal to the resulting value: 
x=80

Check answer by plugging the solution into the original equation: 
20/100 = 16/80

Determine if the values of each side are equal to each other. If so, the solution is correct: 
0.2=0.2

Solution is correct!

16 is 20% of 80 

Hope this helps :)