XP's answer to Meiyu's Primary 5 Maths question.
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For (a), there are 2 discounts:
1) in-store 10% discount
2) additional 10% discount for paying by credit card
and 1 tax: 7% GST
So you use 90/100 times $1599 twice to calculate final cost after the 2 discounts, then times 107/100 to include GST in the price. In shortcut, you can just times all 3 in a single number line.
Round off to "nearest cents" basically means 2 decimal places.
For (b), similarly but slightly different. Because of subtraction involves, different order of operation involves, so require brackets to ensure the discounts are calculated before including GST. If I do not include the bracket, it will go for multiplications first and the $100 discount will be applied the last (after GST is included), which spoils the working.
1) in-store 10% discount
2) additional 10% discount for paying by credit card
and 1 tax: 7% GST
So you use 90/100 times $1599 twice to calculate final cost after the 2 discounts, then times 107/100 to include GST in the price. In shortcut, you can just times all 3 in a single number line.
Round off to "nearest cents" basically means 2 decimal places.
For (b), similarly but slightly different. Because of subtraction involves, different order of operation involves, so require brackets to ensure the discounts are calculated before including GST. If I do not include the bracket, it will go for multiplications first and the $100 discount will be applied the last (after GST is included), which spoils the working.
Date Posted:
7 years ago
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