Answer :
[tex]\{ {{x+2y=8\ \ \ \ \ \ \ \ \ \ \ } \atop {2x+y=10\ [\times\ (-2)]}}\\\\
\{ { {\ \ x+2y=8\ \ } \atop {-4x-2y=-20}}\\\\
-3x=-12\\
x=\frac{-12}{-3}\\
\boxed{x=4}\\\\
2(4)+y=10\\
8+y=10\\
y=10-8\\
\boxed{y=2}\\\\
x+2y=8\\
4+2(2)=8\\
4+4=8\\ \boxed{8=8}\\\\
2(4)+2=10\\
8+2=10\\
\boxed{10=10}[/tex]
a + 2b = 8
2a + b = 10
b = 10 - 2a
a + 2(10 - 2a) = 8
a + 20 - 4a = 8
-3a = -12
a = 4
4 + 2b = 8
2b = 4
B = 2
2a + b = 10
b = 10 - 2a
a + 2(10 - 2a) = 8
a + 20 - 4a = 8
-3a = -12
a = 4
4 + 2b = 8
2b = 4
B = 2