The positive two-digit integers x and y have the same digits, but in reverse order. Which of the following must be a factor of x + y?
1 Explanation
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Jeffrey Braganza
choosing numbers:
17+71 = 77 (7 & 11 are factors but only 11 is in the answer choice)
29+92 = 121 (11 is a factor)
26+62 = 88 (11 & 8 are factors, but only 11 is in the answer choice)
OR
Say the 2 digit number X is composed of nm
and Y is mn
X + Y = nm + mn = (10.n + m) + (10.m + n) = 11n + 11m = 11(n+m)
1 Explanation