If a two-digit positive integer has its digits reversed, the resulting integer differs from the original by 63. By how much do the two digits differ?	Choose the correct choice from the following options:
A) 3
B) 4
C) 5
D) 6
E) 7
Let’s first label the original two-digit integer as N. We can then say that N = 10A + B, where A is the tens digit and B is the units digit of N.   If this is hard to see let’s try it with a sample number, say 24. We can say the following:   24 = (2 x 10) + 4   24 = 20 + 4   24 = 24   Getting back to the problem, we are given that if the integer N has its digits reversed the resulting integer differs from the original by 63. 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 63 we can say:   10B + A – (10A + B) = 63   10B + A – 10A – B =63   9B – 9A = 63   B – A = 7   Since B is the tens digit and A is the units digit, we can say that the digits differ by 7.   The answer is 7.
<result>E</result>
If a two-digit positive integer has its digits reversed, the resulting integer differs from the original by 63. By how much do the two digits differ?