急,, 中一數學 ["*0nly 2 條問題.,!]

ai) Round prices are $40, $20, $10, $20, $20 respectively; total=$110 ; aii) yes

b) In order to receive discount 20% off, the minimum purchase is $100
From result (a), Henry can already enjoy the discount.
That means, it is estimated that Henry have to pay:
$110 x (1-20%)= $88 as minimun amount.

c) Round up prices: $50, $30, $10, $30, $20; Total=$130
So Maximum amount =$130 x 80% = $104

(a)(i) $ (40 + 20 + 10 + 20 + 20) = $110
(ii) A. Yes

(b) $110 x 20% = $88

(c) total maximum account = 50 + 30 + 20 + 30 + 30 =$160
Discount = $ 160 x 20% = $128

2007-06-20 12:32:27 補充：
其實(b)同(c)應該係乘80%先岩,,不過答案是對的

我自己計架..不過唔知岩唔岩~
b.$107.8
c.$109
希望幫到你~=]