Please help! :) Tue’s math teacher gave 20 four-question pop-quizzes throughout the first semester. Tue remembered that she scored either 75% or 100% on all of the quizzes. If her average quiz grade for the semester is 90%, how many of each score did she earn?

Question

anonymous · Answer

Let x be the number of 75%
Let y be the number of 100%

x + y = 20
(.75x + y) / 20 = .9

It's divided by 20 because it is an average

anonymous · Answer

Now you have 2 equations with 2 unknowns and you can solve