well for starters we have to minus 15 from 40 shown as 40-15 which then gives us 25 dollars to spare for the pages. next we divide 25 by 0.17 and that gives you 147.05882 and since we cant have parts of a page we get rid of the decimal and just keep the 147 . and to check this you would do 0.17 times 147 which gives you 24.99, which is less than 25 dollars and next you would add 24.99 to that former 15 from the setup fee which is shown as 24.99 + 15 which finally gives us 39.99 which indubitably is less than 40. That is all. I hope that this wasn't too confusing and if there are any wrong parts please do correct me . Thank you