Solved by JuanFMontesinos in post #2 
              
              
                I think if you understand the meaning of Ax=b it’s straightforward 
Basically you have to figure out A and b 
for a) 
A=(1,1) 
(1,-1) 
and b = (5,1) 
in the example 
b) 2x+2=x-y → x+y=-2 
then 
A = (1,1) 
(3,2) 
b=(-2,0) 
Obtaining A and b allow you to rewrite the problem in a matricial way reusing …