Hey there!
If she missed 4 problems, and that took off 20%, that means 4 is 20% of the total items.
20% is the same as 1/5 of the total amount, since there are 5 20s in 100.
So, we can simply multiply 4 by 5 to get the total amount of problems.
4 x 5 = 20
This means there were 20 problems on the test.
Hope this helps!
