數學問題？？？？？？？？

2. A shop keeper bought 80 dozens of oranges for $1200.
(a) If he wents to make a profit of 40%, what is the selling price of each orange?

1200 ÷ 80(12) x ( 1 + 40% )
= 1200 ÷ 960 x 140%
= 1.25 x 140%
= 1.75 //
If he wents to make a profit of 40%, the selling price of each orange is $1.75.
(b) After 800 oranges are sold, he found that the rest of them are rotten.
Find the overall profit per cent or loss per cent.
[(800 x 1.75) - 1200] ÷ 1200 x 100%
= 200 ÷ 1200 x 100%
= 1/6 x 100%
= 50/3 %
= 16.7 % // ( corr.to 3 sig. fig.)
The overall profit per cent is 16.7%

2.(a) selling price: 1200x (1+40%)/(80x12)=$1.75/each
(b) income: 800x1.75=$1400
profit gained: (1400-1200)/1200 x100%=16.6%

(a)21
(b)我唔知道,sorry!

全英!!!
不明白啊!!!