Suppose that speeding fines are determined by the linear function f(x)=10(x-65)+50, x > 65, where f(x) is the cost in dollars of the fine if a person is caught driving x miles per hour.

a. Radar clocked a driver at 76mph. How much was the fine?

b. While balancing his checkbook, a person ran across a canceled check that his wife had written to the Department of Motor Vehicles for a speeding fine. The check was written for $100. How fast was his wife driving?

c. At what whole-number speed are tickets first given?

d. For what speeds is the fine greater than $200?