Total earnings = $117
Total hours = 17
Earnings on each job:
Baseball coaching per hour = $6
Gym per hour = $9
So, we have to write an equation:
x= number of hours at baseball cocaching
y= number of hours working at the gym
The system of equations:
x+y= 17 (a)
6x+9y=117 (b)
Solve (a) for x:
x=17-y
Replace x on (b) and solve for y:
6(17-y)+9y=117
102-6y+9y=117
-6y+9y =117-102
3y= 15
y=15/3
y=5
Replace y on (a) ans solve for x:
x+5 = 17
x=17-5
x= 12
Hours worked at the gym (y)= 5
Hours worked at basesball (x)= 12