Answer: 37
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Work Shown:
T = tens digit of the original number
U = units digit of the original number
U+T = 10 since the digits add to 10. Solve for U to get U = 10-T
10T+U = original number
10U+T = new number where digits are reversed
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new number = (old number) + 36
10U+T = (10T+U)+36
10U+T = 10T+U+36
10(10-T)+T = 10T+10-T+36 ... plug in U = 10-T
100-10T+T = 10T+10-T+36
-9T+100 = 9T+46
100-46 = 9T+9T
54 = 18T
18T = 54
T = 54/18
T = 3 is the tens digit of the original number
U = 10-T
U = 10-3
U = 7 is the units digit of the original number
10T+U = 10*3+7 = 30+7 = 37 is the original number
73 is the reversed number.
73-37 = 36 is the difference, showing that 37 increased by 36 leads to 73. The answer is confirmed.