Question

Mary babysits for $4 per hour. She also works as a tutor for $7 per hour. She is only allowed to work 14

hours per week but she wants to make at least $56. How many hours at each job should Mary work?

Answer 1

Let x = hours worked as a baby sitter

y = hours worked as a tutor

4x + 7y ≥ 56

x + y ≤ 14

Let's make this easier and switch one some symbols

4x + 7y = 56

x + y = 14

Let's use elimination method; multiply the bottom equation by -4

4x + 7y = 56

-4(x + y = 14)

4x + 7y = 56

-4x - 4y = -56

3y = 0

Divide both sides by

3y/3 = 0/3

y = 0

Plug in the new y into one of the original equation, I'll use the bottom one

x + 0 = 14

x = 14

She can work 14 hours as just a baby sitter and she'll be okay

How about her tutor job? If she just worked her tutor job, she would make more money.

4(0) + 7(14) ≥ 56

98 ≥ 56

It's up to her how many hours to work as long as it's 14 or less

Personally, I would just quit the baby sitting job and just tutor