Question

David has a score of 89 for each of his first 3 math quizzes. The score on his fourth quiz is 92. What score does he need on his fifth quiz to have an average of 90?

i have to show my work btw

Answer 1

91

Explanation:

89+89+89+92+x / 5= 90

359+x / 5= 90 (multiply by 5 both sides)

359+x =450 (subtract 359 from both sides)

X= 91