Question

2x-y=0
5x+2y =27 são duas contas juntas !!

Answer 1

$\boxed{ \left \{ {{2x-y=0} \atop {5x+2y=27}} \right. } \\ \\ - y = 0 - 2x \\ \\ \\ 5x+2y=27 \\ 5x + 2(0 -2x) = 27 \\ 5x - 4 x = 27 \\ x = 27 \\ \\ \\ \\ -y = 0 - 2x \\ -y = -2*27 \\ -y = -54*(-1) \\ y = 54$