Решите уравнение(x+y)-(x-y)=4

Question

Решите уравнение(x+y)-(x-y)=4

Answer 1

2х+2у=4
4ху=4
ху=4/4
ху=1

Answer 2

(x+y)-(x-y)=4
x+y-x+y=4
2y=4
y=2