9514 1404 393
Answer:
72
Explanation:
The difference of 45 means the difference of digits in the number is 45/9 = 5. So, the ones digit is 7-5 = 2, and the number is 72.
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If you want an equation, you can use x for the ones digit.
70 +x = 45 +(10x +7)
18 = 9x . . . . . . . . . . . . . subtract 52+x from both sides
2 = x
The ones digit is 2, so the number is 72.
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Further explanation
If you start with the two digits xy in a number and reverse them, the difference between the numbers xy and yx is ...
(10x +y) -(10y +x) = 9(x -y)
This tells you the difference between the digit-reversed numbers is 9 times the difference between the digits.