The two main formulas you need for this are the following:
1. To add 50% purchase tax to the original price of something, multiply by 1.5.
Why 1.5?
because u are increasing the price so you do
1 + the decimal value of the % you want to increase.
2. To subtract 35% purchase tax from the selling price, divide by 1.35.
Example Question.
Q: There is 15% purchase tax on a suit which costs $450. Calculate the amount to be paid in total.
A: $450 * 1.15
Q: Marks & Spencers are feeling generous and are offering a discount of flat 30% on its tees. Calculate the new price of a tee that costs $520.
A: 520 / 1.30
