Question

Решите систему уравнений

Answer 1

x-2y=5
y-x=-11

x=5+2y
y-5-2y=-11
-y=-6
y=6

x=5+2×6
x=17.

Answer 2

x-2y=5
y-x=-11

y=-11+x

x-2(-11+x) =5
x-22+2x=5
3x=27
x=9

y=-11+9
y=2