Answer:
x represents hours of babysitting
y represents hours of music lesson
hours on babysitting: 11
hours on music lessons: 7
Step-by-step explanation:
x+y=18
5x+12y=139
-5(x+y=18)
=-5x-5y=-90
(5x+12y=139) + (-5x-5y=-90)
7y=49
y=7
x+7=18
x=11
