Answer:
20
Step-by-step explanation:
Patrica got 80% correct. She missed 4 problems, so that must have been the remaining 20% of the test.
Therefore:
4 = 20% x
Percent means out of 100, so:
4 = (20/100) x
4 = 1/5 x
x = 20
There were 20 problems on the test.
