有關f2既maths問題

1)Last year, the marked price and the selling price of a new digital camera were $7200 and $6120 respectively. But this year the marked price and the selling price are adjusted to $6400 and $5600 respectively. In comparing the discount per cent of these two years, which one is greater?
a) discount per cent last year = (7200 – 6120)/7200 * 100% = 15%
b) discount per cent this year = (6400 – 5600)/6400 * 100% = 12.5%
The discount percent last year is greater
2) A computer game software marked at $280 is sold at 20% off. If the discount is 35% of its cost price, find the profit per cent.
The discount is $280 * 20% = $56
The selling price is $280 - $56 = $224
The cost price = $56 / 35% = $160
The profit percent = (224 – 160)/160 * 100% = 40%