Suppose, i have an expression (x + y) xor (w + z). So can i write this expression to this

x xor w + x xor z + y xor w + y xor z ??

No can’t.

(9 + 3) {\oplus} (2 + 13) = 12 {\oplus} 15 = 3

(9 + 3) {\oplus} (2 + 13) = (9 {\oplus} 2) + (9{\oplus}13) + (3{\oplus}2) + (3{\oplus}13) = 30

so, what will be the correct evaluation of this expression??

Where do you need this?? I don’t think you can simplify this further