Question

Porfavor com conta
2x-y=5
x+3y=13

Answer 1

2x-y=5(3)
x+3y=13

6x - 3y = 15
  x + 3y = 13
      7x = 28
       x = 4

2x-y=5 ==> y = 2x - 5 ==> y = 2.4 - 5 ==> y = 8-5 ==> y = 3

Answer 2

-y=5-2x   . (-1)                                      
y=-5+2x

x+3y=13
x+3(-5+2x)=13
x-15+6x=13
x+6x=13+15
7x=28
x=+28/7
x=+4
y=-5+2x
y=-5+2.(+4)
y=-5+8
y=+3