Answer:
Step-by-step explanation:
7. Let the price of book be x
:- 8x + 17 = 129
8x = 129 - 17
8x = 112
x = 112/8
x = $14
Each book cost $14
8. Let the number of hours be x
9x + 15 = 87
9x = 87 - 15
9x = 72
x = 72/9
x = 8hrs
He paid for 8hours
9. Let the numbers be x, x +2, x +4,
So. x + x + 2 + x + 4 = 168
3x + 6 = 168
3x = 168 - 6
3x = 162
x = 162/3
x = 54
The smallest number is 54
10. Let the number of books be x
So, x/2 + 6 = 18
x/2 = 18 - 6
x/2 = 12
x = 12 ×2
x = 24
So she has 24 book's before
