Judy got 117 problems right on a math test in her night school class. She got a score of 78% right. How many problems were on the test?

You would set this up as Part:Whole=Percent:100

Part=117

Whole = X

Percent=78

117:X=78:100

Set these up as fractions and cross multiply. You will get 117*100=78X

117*100=11,700

Divide both sides by 78 and you get x=150

There were 150 problems