Amount Isn't Calculating or Am I Dong it Wrong?

I'm creating a form that sells tickets for $50. I created an "amount" field so the user can enter the amount they would like to purchase. When I enter 3 in the amount field and click "Next" to go to the next page, it shows the amount of $50 and the number of tickets, which is 3. The data shown is correct but;

1. Maybe I'm doing something wrong as I was hoping that when I entered 3 in the "amount" field it would automatically show me the TOTAL of $150 (so the user knows what they are expected to pay). This also means that each time I have to click on "Process Payment" in order to know if the calculations are working correctly. This is my fee formula: [FORM_AMOUNT]*[FIELD_VALUE].

2. Also, I entered a description in the "amount" (pf_amount) field in the back-end but it doesn't show in the front-end, what am I missing?

Any suggestions...

Did you tick the box for the fee field? I forgot to do that and was wondering where my wrong amounts came from.
If you don't sell too many tickets at once, maybe it is more usable if you choose a pull-down list with numbers from 0-9 and aput fees from 0-450 into the fee field. Like this you won't depend on the calculation formula.