Compute both compositions $F \circ G$ and $G \circ F$ of the following affine transformations on $\mathrm{R}^2$. Which pairs commute? (a) $F=$ counterclockwise rotation around the origin by $45^{\circ}$; $G=$ translation in the $y$ direction by 3 units. (b) $F=$ counterclockwise rotation around the point $(1,1)^T$ by $30^{\circ} ; G=$ counterclockwise rotation around the point $(-2,1)^T$ by $90^{\circ}$. (c) $F=$ reflection through the line $y=x+1 ; G=$ rotation around $(1,1)^T$ by $180^{\circ}$.