Cost of 12 copies that Melissa needs to pay = $0.66
Then
Cost of 1 copy that Melissa needs to pay = (66/12) dollars
= 11/2 dollars
Now
The cost of 56 copies that Melissa has to pay =(11/2) * 56
= 11 * 28 dollars
= 308 dollars
So Melissa needs to pay $308 for 56 copies.I hope the procedure is clear enough for you to understand. In future you can use this procedure to solve similar problems in future.