Question

Resolução x+y=15 e 2x+4y=54

Answer 1

x+y=15
2x+4y=54

y=15-x
2x+4y=54
2x+4.(15-x)=54
2x+60-4x=54
2x-4x=54-60
-2x=-6.(-1)
x=6/2
x=3

x+y=15
3+y=15
y=12