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UI Post-UTME Mathematics 2013 Question 2

Question 2

Linear and Simultaneous Equations

The sum of the digits of a 2-digit number is 8. When the digits are interchanged, the new number exceeds the original number by 18. Find the original number?

  1. A.35
  2. B.26
  3. C.17
  4. D.71
Show the answer and explanation

Answer: A (35)

Explanation

A + B = 8 and 9(B − A) = 18, so B − A = 2: A = 3, B = 5, giving 35 (53 − 35 = 18).