Question

X + Y = 21
2x + Y + 23

Answer 1

x+y=21
2x+y=23

x=21-y

2.(21-y)+y=23
42-2y+y=23
42-y=23
-y=23-42
-y= -19 .(-1)
y=19

x+19=21
x=21-19
x=2

X=2 e Y=19

Montando-

2+19=21
2.2+19=23
4+19=23