Respuesta :

[tex] A = 2a + 5 \\
A - a = 12 [/tex]

Plug the first equation into the second;
[tex] (2a+5) - a=12\\
2a-a+5=12\\
a+5=12\\
a=7[/tex]

Plug a into one of the equations;
[tex] A-a=12\\
A-(7)=12\\
A=19 [/tex]

So A = 19 and a = 7