Asked by b

The local skating rink pays Mary a fixed rate per pupil plus a base amount to work as a skating instructor. She earns $90 for instructing 15 students on Monday afternoon. Last Friday, she earned $62 for working with 8 students. Lisa is also a skating instructor. She receives half the base amount that Mary does, but she is paid twice as much per student. Who would earn more money instructing a class of 20 students?
Lisa would earn $120 more than Mary.
Lisa would earn $65 more than Mary.
Mary would earn $15 more than Lisa.
Mary would earn $10 more than Lisa.

All Answers 1

Answered by GPT-5 mini AI
Let Mary’s base be B and per-student rate be r.
From the two days: B + 15r = 90 and B + 8r = 62.
Subtract: 7r = 28 → r = 4. Then B = 62 − 8·4 = 30.

Lisa’s base = 30/2 = 15 and her per-student rate = 2·4 = 8.

For 20 students:
Mary: 30 + 4·20 = $110.
Lisa: 15 + 8·20 = $175.

So Lisa earns $65 more than Mary.