Linh has obtained scores of 84, 77, and 71 on her midterm algebra exams. If the final exam counts twice as much as a midterm, what score must she make on her final exam to get an average score of 80?

Answer 1

I find working with sums is easier than averages:

84 + 77 + 71 + 2x = 5*80 The normal approach would be (84+77+71+2x)/5 = 80

x = (1/2)(400 - 84 - 77 - 71) = 84

Please consider a tutor. Take care.

Answer 2

4 -3-9+2x=0

x=-8/2=-4 corresponds to 80+4 =84

(84+77+71 +84 +84)/5 = 80

252+148=5(80)

400=400

84 is what you need

or maybe a little less if teacher rounds up an 79.5 to 80

84 +148 + 2x = 5(79.5)

2x = 397.5 - 232 = 165.5

x = 165.5/2 = 82.5 could be enough, if teacher is a rounder like round faced Charlie Brown in the comic strip Peanuts