Question

mariana averaged 71 on her first three exams. the first score was 69 and the second score was 2 less than the third score. what did she score on the second and third exam

Answer 1

2nd: 71 3rd: 73

Explanation:

if mariana averaged 71 on her first three exams, it means in total, she scored 71*3 (213 points). since mariana scored 69 for her first exam, the other two exam scores must be 213-69 (144).

using systems of equations, we can identify two equations:

x is the first test, y is the second test, so x<y

x+y=144

x-y=-2

2y=144-(-2)

2y=146

y=73

if you plug in y (73), you can solve for x

x+73=144

x=144-73

x=71