Adding numerical values to drop down options in conditional statements

Adding numerical values to drop down options in conditional statements

I am making a custom form through the dynamic content that deals with buying items through paypal etc. I'm trying to make it so that I can add in financial aid meaning a discount is given and the amount of discount depends on the option they select from the drop down. Currently, when I submit the formula, it does not give me an error message, but instead, erases my IF ELSE statements with no notification. I have net amount on the bottom as an amount the form calculates based on the price of the item and how many items are selected. Here is my coding.

Net_Amount.round(2)

if(Financial_Aid_please_enter_family_income=="$19, 999 and below")
{
Net_Amount=Choose_Items*.8
}else
if(Financial_Aid_please_enter_family_income=="$20, 000 to $39, 999")
{
Net_Amount=Choose_Items*.6
}else
if(Financial_Aid_please_enter_family_income=="$40, 000 to $59, 999")
{
Net_Amount=Choose_Items*.4
}else
if(Financial_Aid_please_enter_family_income=="$60, 000 to $79, 999")
{
Net_Amount=Choose_Items*.2
}else
if(Financial_Aid_please_enter_family_income=="$80, 000 to $99, 999")
{
Net_Amount=Choose_Items*.1
}else
if(Financial_Aid_please_enter_family_income=="$100, 000 and above")
{
Net_Amount=Choose_Items*1
}