Question

{9х+2у=-19/7
{у-х=10/21

Answer 1

{у=10/21+х
{9х+2(10/21+х)=-19/7
9х+20/21+2х=-19/7
11х=-19/7–20/21
11х=(–57–20)/21
11х=-77/21
х=-77/(21•11)
х=-1/3
у=10/21–1/3=(10–7)/21=3/21=1/7