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Question 624491: The sum of the digits of a 2-digit number is 9. The digits are reversed and the new number is substracted from the original numbe, to get 45. Find the original number.
(to be solved in Linear equation with one variable)
Answer by meghraj(2)   (Show Source):
You can put this solution on YOUR website! Let the first digit be x and the second digit be y.
then by question,
x + y = 9
=> y = 9 - x ------- eq 1
Again,
Since the number is 10x+y when it is revered then the number becomes 10y + x.
Therefore, we get by question
=> 10x + y -(10y + x) = 45
=> 10x + y - 10y - x = 45
=> 9x -9y = 45
=> x - y = 5
=> x = 5+y
=> x = 5 + (9-x) -----frm eq 1
=> x = 5 + 9 - x
=> 2x = 14
=> x = 7
Now, eq 1
y = 9 - x
=> y = 9 - 7
=> y = 2
Therefore the number is 72
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