Larson has a score of 89 for each of his first three science
quizzes. the score on his fourth quiz is a 92. what score
does he need on the fifth quiz to have an average of exactly
90?

91%

Step-by-step explanation:

(89+89+89+92)/4 = 89.75%

To get exactly 90, he would need a 91% because a number between 89-92 is 91. Also, you can just guess and check on the calculator!

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so:

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