Lucy bought one massage chair at 20% discount off its original price. She paid a total of $856 for it, which was inclusive of 7% GST on the discounted price. What was the original price of the massage chair?

	Percent expressed as units	Percent expressed as %	Amount
Original price	100 u		?
Discount	- 20 u
Discounted price	80 u	100%	$800
GST		+ 7%
Amount to pay		107%	$856

Price of the massage chair with 7% GST in percent
= 100% + 7%
= 107%

107% of the massage chair with 7% GST = 856
1% of the massage chair with 7% GST = 856 ÷ 107 = 8
100% of the massage chair with 7% GST = 100 x 8 = 800

Price of the massage chair at 20% discount in units
= 100 u - 20 u
= 80 u

Discounted price = 100% of the price to pay for before adding GST.

80 u of the massage chair without GST = 800
1 u of the massage chair without GST = 800 ÷ 80 = 10
100 u of the massage chair without GST = 100 x 10 = 1000

Original price of the massage chair = $1000

Answer(s): $1000