Rachel bought one computer at 25% discount off its original price. She paid a total of $642 for it, which was inclusive of 7% GST on the discounted price. What was the original price of the computer?
| |
Percent expressed as units |
Percent expressed as % |
Amount |
| Original price |
100 u |
|
? |
| Discount |
- 25 u |
|
|
| Discounted price |
75 u |
100% |
$600 |
| GST |
|
+ 7% |
|
Amount
to pay |
|
107% |
$642 |
Price of the computer with 7% GST in percent
= 100% + 7%
= 107%
107% of the computer with 7% GST = 642
1% of the computer with 7% GST = 642 ÷ 107 = 6
100% of the computer with 7% GST = 100 x 6 = 600
Price of the computer at 25% discount in units
= 100 u - 25 u
= 75 u
Discounted price = 100% of the price to pay for before adding GST.
75 u of the computer without GST = 600
1 u of the computer without GST = 600 ÷ 75 = 8
100 u of the computer without GST = 100 x 8 = 800
Original price of the computer = $800
Answer(s): $800
