Answer: 6 ≤ h ≤ 9
Step-by-step explanation:
Hi, since He charges $40 as a fixed rate for the first hour plus $20 for each additional hour, the cost of the tutoring service is equal to the fixed rate(40) plus, the product of the additional hours (h-1) and the cost per additional hour (20).
40+20(h-1)
40+20h-20
20+20h
Since a student can spend between $140 and $200, the previous expression must be greater o equal than 140, and less or equal than 200.
140≤20+20h≤200
Subtracting 20
140-20 ≤20-20+20h ≤200-20
120 ≤ 20h ≤ 180
Dividing by 20
120/20 ≤ 20h/20 ≤ 180/20
6 ≤ h ≤ 9