A furniture store was having Christmas discount of 25% off its usual price. The GST is at 7%. Xylia used her credit card to purchase a dining table and Michael used cash to pay for a similar dining table.

1. How much did Xylia pay in the end after GST? Round off your answer to the nearest cent.
2. How much did Michael pay in the end after GST? Round off your answer to the nearest ten cent.

New dining table Usual Price: $640

Further Discount: Pay by credit card: 15% off discounted price before GST! Pay by cash: $10 off discounted price before GST!

	Credit Card	Cash
Usual Price	$640	$640
Less 25% discount	- $160.00	- $160.00
Price after 25% discount	$480.00	$480.00
Less further discount	- $72.00	- $10
Price after further discount	$408.00	$470.00
Price after GST of 7%	$436.56	$502.90

(a)
New selling price after 25% discount
= 100% - 25%
= 75%

Price of the dining table after Christmas discount
= 75% x 640
= ⁸⁵₁₀₀ x 640
= $480.00

New selling price after 15% further discount
= 100% - 15%
= 85%

Price of the dining table after credit card discount
= 85% x 480.00
= ⁸⁵₁₀₀ x 480.00
= $408.00

Price to pay after including GST
= 100% + 7%
= 107%

Price of the dining table after GST
= 107% x 408.00 
= ¹⁰⁷₁₀₀ x 408.00 
≈ $436.56 (Round off to nearest cent)

(b)
Price of the dining table after cash discount
= 480.00 - 10
= $470.00

Price of the dining table after GST
= 107% x 470.00 
= ¹⁰⁷₁₀₀ x 470.00 
≈ $502.90 (Round off to nearest ten cent)

Answer(s): (a) $436.56; (b) $502.90