This is a math question

Question

Karen makes $5 per hour babysitting and $12 per hour giving music lessons. One weekend, she worked a total of 18 hours and make $139. How many hours did she spend babysitting?

Answer 1

Given,

"b" represents hours babysitting

"m" represents hours giving music lessons

5b + 12m = 139 (represents money made)

b + m = 18 (represents hours worked)

Solve the system using elimination:

I want to solve for "b" (babysitting hours), so I'll look to eliminate "m".

5b + 12m = 139

-12b - 12m = -216 (multiply the 2nd equation by -12, so my "m" eliminates when I combine my equations)

-7b = -77 (divide -7 on both sides)

b = 11 hours babysitting