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標題:
一條中二的數學題;?
The sum of the units digit and the tens digit of a two-digit number is 15.If the two digits are interchanged,the new number is 9 greater than the original number. Find the original number. HELP!唔識呀!
最佳解答:
Let a be the unit digit, and b be the ten digit. a+b = 15...i 10b+a - 10a-b = 9 9b-9a = 9 ..ii From (i), b= 15-a...(iii) Sub (iii) into (ii), 9(15-a)-9a = 9 135-9a-9a = 9 18a = 126 a = 7 Sub a= 7 into (iii), b = 15-7 b = 8 So that the original number is 78.
其他解答:
一條中二的數學題;?
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發問:The sum of the units digit and the tens digit of a two-digit number is 15.If the two digits are interchanged,the new number is 9 greater than the original number. Find the original number. HELP!唔識呀!
最佳解答:
Let a be the unit digit, and b be the ten digit. a+b = 15...i 10b+a - 10a-b = 9 9b-9a = 9 ..ii From (i), b= 15-a...(iii) Sub (iii) into (ii), 9(15-a)-9a = 9 135-9a-9a = 9 18a = 126 a = 7 Sub a= 7 into (iii), b = 15-7 b = 8 So that the original number is 78.
其他解答:
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