數學題~~急急急~~

1)
x/7-28 = 9
x/7 = 9+28
x/7 = 37
x = 259

20
2x/3-9 = 15
2x/3 = 15+9
2x/3 = 24
2x = 72
x = 36

3)
x/18 - 1 1/4 = 5/6
x/18 = 5/6 + 5/4
x/18 = 25/12
x= 37 1/2

首先這裡先說我所打的y分之x是等同x/y ,明白??

1. ans: x/7 - 28 = 9
x/7 - 28 + 28 = 9 + 28
x/7 = 37
x/7 X 7 = 37 X 7
x = 259

2. ans: 2x/3 - 9 = 15
2x/3 - 9 + 9 = 15 + 9
2x/3 = 24
2x/3 X 3 = 24 X 3
2x/2 = 72/2
x = 36

3. ans: x/18 - 1又4分1 = 5/6
x/18 - 5/4 = 5/6
x/18 - 5/4 + 5/4 = 5/6 + 5/4
x/18 = 10/12 + 15/12
x/18 = 25/12
x/18 X 18 = 25/12 X 18
x = 75/2 or 37.5

參考資料：(1)分數之加減乘除，一定要將帶分數轉為假分數才可計算　（第三題）
(2)分數加減一定要分母一樣,若不一樣便要用L.C.M方法啦(第三題)
好像第三題中的分母是4,6,他們L.C.M是12,但由於分母已經乘了一個數值,
所以分子也要乘同一個數值
(3)我開始是否說了y分之x 等同 x/y ,其實y分之x也等同x除y

(x-28)/7=9
x-28=63
x=91//

(2x-9)/3=15
2x-9=45
2x=54
x=27//

(x-1)/18+1/4=5/6<----e 題我唔comfirm
2(x-1)/36+9/36=30/36
2x-2+9=30
x=6.5///

1)28+7/9
2)4.6
3)唔知你講咩

1. x=223
2. x= 62
3. x= 37.5

2007-08-13 15:38:56 補充：
唔知right or not~ 唔好信哂,,都係自己計啦

自已的功課自已做！！！！