2l = 13 and 5l = 32.5 After simplifying these we get: L = 6.5. In context, this means that one yard of fabric costs $6.50. As the number of yard of fabric increases, cost increases, so c = 6.5l.
I can not raise the exponent but there is 4, 15 being multiplied together and all you do is add how many of the same numbers are being multiplied together.