The most important part of the problem lies in the fact that the hours have to be converted to minutes before starting to solve the problem.
1 hour = 60 minutes
6 and half hours = (6 * 60) + 30 minutes
= 360 + 30
= 390 minutes
So the payment for 390 minutes is = 78 dollars
Then
The payment for 60 minutes = (78/390) * 60
= 2 * 6 dollars
= 12 dollars
So the rate of pay given is $12 per hour. I hope the procedure is easy enough for you to understand. You can always use this method for solving similar type of problems.
