unsure of what to call it yet system 1.2

It has been a busy time with developing lately, I have managed to get all the formulas working for calculating to cost of producing a book. First try of it failed as it did not include the cost of designing a cover. Second time failed as I included the cost of GST at 12.5%, which I found out php doesn't like. Always go back to year 9 maths and GST = 1.125, its a lot easier.

Test tried it on a few quotes and I came back with the approx quote that had been sent to the client. This one is pretty much dead on. Though we did find one flaw. It calculates the number of pages in a book on wordcount, what happens when you are given the number of pages in the book. I am thinking I might have to include a variable to multiply the number of pages, or state the number of pages so it can calculate.

if $wordcount='' || $pages ='' then fail

if $wordcount =xx { }

else if $pages = xx { }

else exit();