(X+Y)-(X-Y)=20

Solution for (X+Y)-(X-Y)=20 equation:

Simplifying
(X + Y) + -1(X + -1Y) = 20

Remove parenthesis around (X + Y)
X + Y + -1(X + -1Y) = 20
X + Y + (X * -1 + -1Y * -1) = 20
X + Y + (-1X + 1Y) = 20

Reorder the terms:
X + -1X + Y + 1Y = 20

Combine like terms: X + -1X = 0
0 + Y + 1Y = 20
Y + 1Y = 20

Combine like terms: Y + 1Y = 2Y
2Y = 20

Solving
2Y = 20

Solving for variable 'Y'.

Move all terms containing Y to the left, all other terms to the right.

Divide each side by '2'.
Y = 10

Simplifying
Y = 10