y>= x +3
y<= 3-x
Draw the line $\displaystyle y=x+3$, then the first inequality is satisfied by points on and above the line.
Draw the line $\displaystyle y=3-x$, then the second inequality is satisfied by points on and below the line.
Both are satisfied by points on and above $\displaystyle y=x+3$ and on or below $\displaystyle y=3-x$
CB