Respuesta :
[tex]a-b=21 |\cdot(-2)\\
5a-2b=18\\\\
-2a+2b=-42\\
\underline{5a-2b=18}\\
3a=-24\\
a=-8\\\\
-8-b=21\\
b=-29
[/tex]
[tex]a-b=21 \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ |\times (-2) \\
5a-2b=18 \\ \\
-2a+2b=-42 \\
\underline{5a-2b=18 \ \ \ \ \ \ \ } \\
5a-2a=18-42 \\ 3a=-24 \\
a=\frac{-24}{3} \\
a=-8 \\ \\
a-b=21 \\
-8-b=21 \\
-b=21+8 \\
-b=29 \\
b=-29[/tex]
a=-8 and b=-29.
a=-8 and b=-29.