The math problem has a subtraction formula, the subtracted plus the subtracted, plus their difference, the sum is 512, the subtraction is 125, how to get the formula

The math problem has a subtraction formula, the subtracted plus the subtracted, plus their difference, the sum is 512, the subtraction is 125, how to get the formula

Subtracted = subtracted + difference
Subtracted = 512 / 2 = 256
The difference is 256-125 = 131