異分母分數加減(1個鐘內答,急用~)

1.爸爸買了一個薄餅回家,小文吃了4分之一個,小桐吃了6分之一個,還餘簿餅多少個?
1 - 1/4 - 1/6
= 12/12 - 3/12 - 2/12
= (12-3-2)/12
= 7/12

2.小美帶了一瓶橙汁,上午喝去12分之5瓶,下午喝去10分之3瓶.小美餘下多少橙汁?
= 1 - 5/12 - 3/10
= 60/60 - 25/60 - 18/60
= (60-25-18)/60
= 17/60

3.子恩用5分之2杯芒果汁和2分之1杯蘋果汁做了一杯果汁,喝了4分之3杯後,還餘下多少果汁呢?
= 2/5 + 1/2 - 3/4
= 8/20 + 10/20 - 15/20
= (8+10-15)/20
= 3/10

4.原有花布2又10分之9米,用去1又6分之5米後,再買多花布1又3分之2米,現有花布多少米?
= (2+9/10) - (1+5/6) + (1+2/3)
= (60/30 + 27/30) - (30/30 + 25/30) + (30/30 + 20/30)
= (60+27-30-25+30+20)/30
= 82/30
= 2又22/30
= 2又11/15

2007-10-07 19:40:51 補充：
(第3條答案打錯了, 應是3/20)3.子恩用5分之2杯芒果汁和2分之1杯蘋果汁做了一杯果汁,喝了4分之3杯後,還餘下多少果汁呢?= 2/5 + 1/2 - 3/4= 8/20 + 10/20 - 15/20= (8+10-15)/20= 3/20

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1. 1-1/4-1/6 = 12/12 - 3/12 - 2/12 = 7/12

2. 1-5/12-3/10 = 60/60 - 25/60 - 18/60 = 17/60

3. 2/5+1/2-3/4 = 8/20 + 10/20 - 15/20 = 3/20

4. 29/10 - 11/6 + 5/3 = 87/30 - 55/30 + 50/30 = 18/30

1. 7/12

2. 17/60

3. 3/20

4. 18/30

1.
1 - 1/4 - 1/6 = 1 - 3/12 - 2/12 = 7/12

2.
1 - 5/12 - 3/10 = 1 - 50/120 - 36/120 = 34/120 = 17/60

3.
2(9/10) - 1(5/6) + 1(2/3)

= 29/10 - 11/6 + 5/3 = 87/30 - 55/30 + 50/30
= 82/30 = 2(22/30)
= 2(11/15)

1. ) 1 - 4分1 - 6分1 = 12分12-12分3-12分2 = 12分7
2.) 1 - 12分5 - 10分3 = 60分60 - 60分25 -60分18 = 60分17
3.) 5分2 + 2分1 -4分3 = 20分4 + 20分10 - 20分15 = 20分3
4.) 2又10分9 - 1又6分5 +1又3分2 = 30分87 - 30分55 + 30分50 = 15分41 = 2又15分11

1.1-(1/4+1/6)


2.12/5+10/3

3.5/2+2/2-4/3

4.2 10/9-1 6/5+1 3/2

2007-10-07 19:21:52 補充：
1=7/122 = 17/603 = 3/204 = 18/30

1. 1-1/4-1/6 = 12/12 - 3/12 - 2/12 = 7/12

2. 1-5/12-3/10 = 60/60 - 25/60 - 18/60 = 17/60

3. 2/5+1/2-3/4 = 8/20 + 10/20 - 15/20 = 3/20

4. 29/10 - 11/6 + 5/3 = 87/30 - 55/30 + 50/30 = 18/30