Question

Shayla tutors middle school students and high school students. She charges a different rate for each. Last week, she tutored middle school students for 5 hours and high school students for 12 hours. This week, she tutored middle school students for 6 hours and high school students for 10 hours. She earned $400 last week and $370 this week. How much does she charge each?

Answer 1

Shayla charges $20 per hour for middle school students and $25 per hour for high school students.

Explanation:

System of Equations

Let's call:

x = Shayla's hourly charge for middle school students

y = Shayla's hourly charge for high school students

Last week, Shayla tutored middle school students for 5 hours and high school students for 12 hours. The total earning was 5x+12y. She earned $400 last week, thus:

5x + 12y = 400 [1]

This week, she tutored middle school students for 6 hours and high school students for 10 hours. The total earnings were 6x+10y and it represented $370, thus:

6x + 10y = 370

Dividing by 2:

3x + 5y = 185 [2]

We have formed the system of equations:

5x + 12y = 400 [1]

3x + 5y = 185 [2]

Multiply [1] by -3 and [2] by 5:

-15x - 36y = -1200

15x + 25y = 925

Adding both equations:

-11y = -275

Dividing by -11:

y = -275/(-11) = 25

y = 25

Substituting in [1]:

5x + 12*25 = 400

5x + 300 = 400

5x = 400 - 300 = 100

x = 100/5 = 20

x = 20

Shayla charges $20 per hour for middle school students and $25 per hour for high school students.