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標題:

求高人指點! 例式

發問:

哥哥的儲蓄較妹妹多$300.當哥哥給了妹妹$450後,哥哥的儲蓄便是妹妹的2/5.問他們的儲蓄共有多少? 求高人指點! 例式 唔該.感激不盡!

 

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最佳解答:

哥-300 = 妹 ... (1) 哥-450 = (妹+450) x 2/5 (2) sub (1) into (2) 哥-450 = (妹+450) x 2/5 哥-450 = (哥-300+450) x 2/5 哥-450 = 2/5哥 +60 3/5哥 = 510 3哥 = 2550 哥 = 850.... (3) sub (3) into (1) 哥 - 300 = 妹 850 - 300 = 妹 妹 = 550 (反代入 哥= 850 妹= 550 (1) 哥哥的儲蓄較妹妹多$300 = (ok) (2) 當哥哥給了妹妹$450後,哥哥的儲蓄便是妹妹的2/5 850 - 450 = (550+450)2/5 400 = 1000 x 2/5 400 = 400 (ok) ) 兩人合共 850+550 = 1400

其他解答:

Let $ of brother be x, $ of sister be y. x-y = 300... (1) x-450 = 2/5 y ....(2) From (1) x = 300 + y ... (3) Put (3) into (2), 300 + y -450 = 2/5y -150 + y = 2/5 y -150 = 2/5y - y 3/5 y = 150 3y = 750 y= 250 Put y= 250 into (1), x-250 = 300 x = 550 Therefore, the sum of x (brother) and y ( sister ) are $ 550 + $ 250 = $ 800|||||300-10.4+450 10.4=2/5化小數 5知啱5啱0D7DAC4E7B8CAAC5

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