小學數學問題

2008-01-03 12:05 am
22-11.5   100-T
------- = -----
22-4.5     100

答案=40 但係究竟點解呢.. 有冇人可以慢慢拆比我睇
thx~

回答 (4)

2008-01-03 12:12 am
✔ 最佳答案
22-11.5   100-T
------- = -----
22-4.5     100

100(22-11.5) =100-T(22-4.5)
100(10.5) =100-T(17.5)
1050 =100x17.5-Tx17.5
1050 =1750-17.5T
17.5T =1750-1050
17.5T =700
T =40

2008-01-02 16:13:33 補充:
交叉相乘,代入去入面
2008-01-03 12:16 am
100(22-11.5)
-------------------- = 100-T
22-4.5 

100(13.5)
-------------------- = 100-T
7.5  

60 = 100-T
60-100 = -T
-40 = -T
T = 40
2008-01-03 12:15 am
22-11.5   100-T
------- = -----
22-4.5     100

 10.5 100-T
----   = ------
17.5 100

10.5 X 100
------  = 100-T
17.5

  10.5 X 100 = (100-T) X 17.5

1050 = 1750 -17.5T

1050 + 17.5T = 1750

17.5T = 1750-1050

17.5T / 17.5 = 700 / 17.5

T = 40
2008-01-03 12:10 am
咪交叉相乘羅.


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