Answer:
11 hours she worked at the grocery store
Step-by-step explanation:
assuming,
the number of hours worked at tutoring = x
the number of hours worked at grocery store = y
which means,
the amount she made at tutoring = x* $15
the amount she made at grocery store = y*$9
we have 2 equations
total number of hours
1) x+y= 15
total amount she earned
2) x* $15+ y* $9= $159
From equation 1
x+y= 15
x=15-y
we replace this x value in equation 2
x* $15+ y* $9= $159
(15-y)* $15+ y* $9= $159
(15*15)- 15y+9y=159
225-6y=159
225-159=6y
66=6y
66/6=y
11=y the number of hours she worked at grocery store.
we place y=11 in our derived x equation
x=15-y
x=15-11
x=4 the number of hours she worked at tutoring.
