Twice the sum of the digits of a two-digit number is 14. The original number subtracted from the number formed when the digits are reversed is 27. What is the original number?
Correct answer:
Since the original number, when SUBTRACTED from the reversed number, is 27, it's obvious that the reversed number will be LARGER than the original number.
Therefore, the original number CANNOT be 52.
Twice the sum of the 2 digits is 24, so sum of the 2 digits is 7.
Let tens digit be T
Then U (units digit) = 7 - T
Original number: 10T + U
Reversed number: 10U + T
We then get: 10U + T - (10T + U) = 27
10U + T - 10T - U = 27
9U - 9T = 27_____9(U - T) = 9(3)_____U - T = 3 ----- eq (i)
7 - T - T = 3 ------ Substituting 7 - T for U in eq (i)
- T - T = 3 - 7
- 2T = - 4
Tens digit or
Units digit: 7 - 2, or 5