Answer
$(x,y) \in R$; Many infinite solutions
Work Step by Step
Since, we have two equations $y=4-x$ and $3x+3y=12$, we have
From the given two equations, we have $y=4-x$
Plug the value of y in $3x+3y=12$, then$3x+3(4-x)=12$
or, $3x+12-3x=12$
or, $12=12$
Thus, $(x,y) \in R$; Many infinite solutions