Rachel was an 85 average after four test. what does she need to earn on the next test if she wants to raise her average to exactly 88?

she took four tests with one more to take totals 5 tests

88 x 5 = 440

all her tests need to equal at least 440 to get an 88 average

since she has 85 average after 4, 85*4 = 340, so her 4 tests so far have equaled 340

440-340 = 100

she will need to get a 100 on her 5th test to have an 88 average