a student earned a grade of 80% on a math test that had 20 problems how many problems on this test did the student answer correctly

16

Step-by-step explanation:

To find 80% of 20, multiply .80 x 20

.80×20 = 16

This is how you multiply percentages--put the decimal point 2 places to the left, then multiply.  In this case, you're looking at 80%, so move the decimal point two places to the left

80.0 becomes .80

Then multiply that by the number you're trying to find the percentage of

add 5 subtract 1

step-by-step explanation: