The difference between a two-digit number and the number obtained by interchanging the two digits of the number is 9. If the sum of the two digits of the number is 15, then what is the original number?
Question
The difference between a two-digit number and the number obtained by interchanging the two digits of the number is 9. If the sum of the two digits of the number is 15, then what is the original number?
=> 9(X-Y) = 9
=> X-Y = 1 --- (1)
=> X+Y = 15 --- (2)
X – digit at ten’s place of the number
Y – digit at unit’s place of the number
solving these two equations, we get X = 8, Y = 7
Now the number may be either 87 or 78
So, answer is cannot be determined.
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