Any proportional relationship will include (0, 0) as a possible (input, output) pair. Here, the one-time fee of $10 means the output for 0 hours is not 0, but is 10. That is (0, 10) is a pair in the relationship, not (0, 0).
To find the total from the percent part you have, you divide the part by the percentage. 1.50÷0.05=30 The total is $30 The total the store charged, including sales tax, is $31.50.
