Use the grid to create a model to solve the percent problem.

21 is 70% of what number?

enter your answer in the box.

For this case we can make the following rule of three:
 21 > 70%
 x > 100%
 Clearing x we have:
 x = (100/70) * (21)
 Rewriting we have:
 x = (10/7) * (21)
 x = 30
 Thus,
 21 is 70% of 30
 
 21 is 70% of 30

The answer would be 10.