Help with Excel functions

You need to give a name to cell B42 if it does not already have one.  highlight that cell and check in the upper left box that shows cell addresses.  If it doesn't say B42, then it has a name.

The formula could be a nested if statement.  Have the first one check the contents of the payment method to see if it says "Rewards", and the if true part of the formula would show the amount charged times the B42 cell, but instead of writing B42, you would click on that cell which should automatically enter the name.  You could also just enter the name.  Then the if false portion of the formula would be the nested IF formula which does the same thing except it check for "Express Miles", with results if true would be the charged amount times that same range name for the discount.  The if false portion of the formula would be zero "0").  You should be able to just copy this down to the rest of the cells.