#2**+1 **

\(\begin{cases}725x + 727y = 1500 \text{ --- }(1)\\729x + 7y = 1508\text{ --- }(2)\end{cases}\)

Subtract (1) from (2) to get

\(4x - 720y = 8\\ x - 180y = 2\text{ --- }(3)\)

Now, solve the system formed by equations (2) and (3) using method of elimination, and you will get \((x, y) = \left(\dfrac{271454}{131227}, \dfrac{50}{131227}\right)\)

Therefore, x - y = \(\dfrac{271404}{131227}\), as robloxDying suggested.

MaxWong Apr 22, 2022