Your two equations are (5a+ 6)x+ ay= 8 and (a+4)x+ y= -4 (wouldn't it have been easier to just type those equations rather than uploading a file- and requiring other to open it?) and, if I read this correctly, you are asking for a value of a such that they reduce to a single equation.
The right hand side terms are -4 and 8, not involving a, and you can go from -4 to 8 by multiplying by -2. So it looks like the first equation is the second equation multiplied by -2. That is, 5a+ 6= -2(a+ 4) and a= -2.