This is a system of equations problem.
L = Hours of Swim Lessons
C = Hours as Cashier
L + C = 15 This is an equation for working 15 hours total.
so
L = 15-C
6L + 8C = 100 This is an equation for making at least $100.
so
6 (15-C) + 8C = 100 *You substituted 15-C for L here
90 - 6C + 8C = 100 Distribute
90 + 2C = 100
2C = 10
C = 5 You can work 5 hours as a cashier
L + C = 15
L + 5 = 15
L = 10 You can work 10 hours teaching swimming lessons.
If you want to make EXACTLY $100 you would work 5 hours as cashier and 10 hours teaching swimming lessons.
HOWEVER, the question says AT LEAST $100 and NOT MORE than 15 hours per week. Since you make more money as a cashier, any work over 5 hours will help you make over $100.
As long as you work at least 5 hours as a cashier and any remaining hours teaching swimming lessons, you will make over $100.
5 cashier, 10 swimming
6 cashier, 9 swimming
7 cashier, 8 swimming...
Mr. Pacey
JH/HS Social Studies Teacher
(but I've also helped with Math Team for JH & HS)
