f.1 英文文字方程

2008-10-13 12:45 am

1.In a stationary shop ,the price of a ruler is less than of a pen by $3,and price of 8 rulers is more than that of 5 pens by $3 . Find the price of a ruler.

2.The length of a rectangle is twice as long as its breadth . If the perimeter is 48 cm , find its area.

3.Mr.Chan's weight is more than twice that of his son John by 9 kg.If the total of John's weight and twice that of Mr .Chan 's weight is 135 kg ,find John's weight .

(麻煩巴打用中文解釋及列方程式,thxxxxx.....)

回答 (1)

Amy

2008-10-13 1:10 am

✔ 最佳答案

1. 在文具店, ruler 的價格 (以下用 r 代表) 比 pen (以下用 p) 的少 $3. 另 8 把 rulers 比 5 支 pens 多 $3. 找 ruler 的價格.

p - r = 3
p = 3 + r

8r - 5p = 3
8r - 5 (3 + r) = 3
8r - 15 - 5r = 3
3r = 18
r = $6

2. 不記得 perimet 的方程式

3. Mr Chan 體重 (以下用 c 代表) 比他兒子 John (以下用 j) 2 倍的體重多 9 kg. 假如 John 體重加 Mr Chan 2 倍體重為 135 kg. 找 John 的體重.

c - 2j = 9
c = 9 + 2j

j + 2c = 135
j + 2 (9 + 2j) = 135
j + 18 + 4j = 135
5j = 117
j = 23.4 kg

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