Question

Maria answered all the problems on her math test. She answered 80 percent of the problems correctly. If she answered 6 problems incorrectly, how many problems were on the test?

Answer 1

Let x = the total number of problems.

0.2x = 6

x = 6/0.2

x = 30

Answer 2

This is a direct proportion problem.

80% correct means 100-80=20% incorrect.

By direct proportions,
20% : 6 problems
100% : X problems?

Cross multiply to get
X=6*100/20=30