Percentages are sometimes difficult to understand. It is important to remember that whichever integer you are using to convert (true or inverse) it is important to use the same integer for the entire formula only changing the operation from quotient to product.
AED 340
4/5=4÷5=.2 (20%) inverse=.8 (80%)
x=(222+50)/.8
x=272/.8
x=340
*proof*
340×.8=272 (20% discount, 4/5=.2)
272-50=222 (AED 50 gift cert.)
