Solve the Problem. -One Internet Service Provider Has the Following Rate Schedule for Rate

Short Answer

Solve the problem.
-One Internet service provider has the following rate schedule for high-speed Internet service:
Monthly service charge $18.00
1st 50 hours of use free
Next 50 hours of use $0.25/hour
Over 100 hours of use $1.00/hour
What is the charge for 50 hours of high-speed Internet use in one month?
What is the charge for 75 hours of high-speed Internet use in one month?
What is the charge for 135 hours of high-speed Internet use in one month?