Mathematical Logic
How the deductions are calculated behind the scenes
Step 1: Extracting Base Price
To find the original base price before an 18% GST was added, we divide the total inclusive price by 1.18.
Base Price = Total Price ÷ 1.18
Step 2: Applying the Discount
The amount you choose to subtract is deducted directly from that extracted base price.
New Base Price = Base Price - Subtracted Amount
Step 3: Recalculating Final Price
Finally, we re-apply the 18% GST to the new base price to find the final total amount.
Final GST = New Base Price × 0.18
Final Price = New Base Price × 1.18
Final Price = New Base Price × 1.18