x of 20% = y
x - y = 75
x = total amount
y = discounted amount
x * 20/100 = y
x * 0.2 = y
replace y with 0.2x in other equation
x - y = 75
1x - 0.2x = 75
0.80x = 75
x = 75/.8
x = 93.75
Check:
93.75 * 20/100 = 18.75
93.75 - 18.75 = 75
x = 93.75
y = 18.75
Answer: Total amount without discount is $93.75
//BTW not sure about this, but kind of make sense
