Question

{3x + Y = 7
{X+3y=-35

Answer 1

{y=7-3x
{x+3(7-3x)=-35

{y=7-3x
{x+14-9x=-35

x-9x=-8x

-8x=-35-14

-8x=-49

x=49/8
x=6.125

y=7-3(6.125)
y=-11.375

Espero ter ajudado!