For a two digit number, the number on the ten digit is 9 less than the square of the number on the individual digit. If you transpose the one digit number and the ten digit number, the two digit number obtained is 27 less than the original two digit number, so you can find the original two digit number

For a two digit number, the number on the ten digit is 9 less than the square of the number on the individual digit. If you transpose the one digit number and the ten digit number, the two digit number obtained is 27 less than the original two digit number, so you can find the original two digit number

Let ten digits be x and one digit be y
Then x = y ^ 2-9
(10x+y)-(10y+x)=27
We get x = 7, y = 4
X = 0, y = 3 (rounding)
A: the original double digit is 74