Before a salary increase, the weekly salary of a worker for 45 hours in a week was as much as the worker is paid now for 40 hours of work in a week. What is the percent increase in the worker's salary per hour?
Choose the correct choice:  A) 5  B) 7.5  C) 8  D) 10  E) 12.5
Let x be the original salary per hour.   Let y be the salary per hour after the increase.   40y=45x   y=(45/40)= 
<gadget id="calculator">(45/40)</gadget>
<output>9/8 = around 1.125</output>
1.125x   The salary increased 12.5%.   The answer is 12.5.
<result>E</result>
Before a salary increase, the weekly salary of a worker for 45 hours in a week was as much as the worker is paid now for 40 hours of work in a week. What is the percent increase in the worker's salary per hour?