If a two-digit positive integer has its digits reversed, the resulting integer differs from the original by 18. By how much do the two digits differ?
Choose the correct choice from the following options
A) 2 B) 3 C) 5 D) 6 E) 7
we are given that if the integer N has its digits reversed the resulting integer differs from the original by 18. First let’s express the reversed number in a similar fashion to the way in which we expressed the original integer.   10B + A = reversed integer   Since we know the resulting integer differs from the original by 18 we can say:   10B + A – (10A + B) = 18   10B + A – 10A – B = 18   9B – 9A = 18   B – A = 2   Since B is the tens digit and A is the units digit, we can say that the digits differ by 2.   The answer is 2.
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If a two-digit positive integer has its digits reversed, the resulting integer differs from the original by 18. By how much do the two digits differ?