Let X and Y be the digits.
If a two-digit number is written XY, then its value is 10x+y.
When the digits of the number are interchanged, it's YX, and its value is 10y+x.
The sum of the digits is 12.
The number formed by interchaning the digits is 54 more than the original number.
The digits X and Y are 3 and 9, so the original number is 39.
5x+3y=12
Subtract 5x from both sides
3y=-5x+12
Divide by 3
Y=-5/3x +4
5625 m^2
If is is square, all sides must be congruent (all sides are 75m). To find area, you multiply width x length (how long). Therefore:
75m x 75m = 5626 m^2