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Applied problems

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by pullagurla » Thu Sep 02, 2010 10:44 pm
If a two-digit positive integer has its digits reversed,
the resulting integer differs from the original by 27.
By how much do the two digits differ?
(A) 3
(B) 4
(C) 5
(D) 6
(E) 7

Use backsolving
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Source: — Problem Solving |

by Rahul@gurome » Thu Sep 02, 2010 10:51 pm
Solution:
Let the two digit positive integer be 10x + y.
On reversing, the new integer is 10y+x.
Difference between them is (10x+y) - (10y+x) =9(x-y).
Since 9(x-y) = 27,
x-y = 3.

The correct answer is (A).
Rahul Lakhani
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