Question

When Susan babysat for 8 hours and did odd jobs for 3 hours, she made a total of $39. When she babysat for 2 hours and did odd jobs for 5 hours, she made a total of $31. How much does she charge per hour for babysitting and for doing odd jobs?

Answer 1

x = charge for babysitting = $3

y = charge for doing odd jobs = $5

Explanation:

Let

x = charge for babysitting

y = charge for doing odd jobs

8x + 3y = 39 (1)

2x + 5y = 31 (2)

Multiply (1) by 5and (2) by 3

40x + 15y = 195 (3)

6x + 15y = 93 (4)

Subtract (4) from (3)

40x - 6x = 195 - 93

34x = 102

Divide both sides by 34

x = 102 / 34

= 3

x = $3

Substitute x = 3 into (1)

8x + 3y = 39

8(3) + 3y = 39

24 + 3y = 39

3y = 39 - 24

3y = 15

y = 15 / 3

= 5

y = $5

x = charge for babysitting = $3

y = charge for doing odd jobs = $5