Optellen geeft \(3a=9\text{,}\) dus \(a=3\text{.}\)

\(\begin{rcases}a-b=5 \\ a=3\end{rcases}\begin{matrix}3-b=5 \\ -b=2 \\ b=-2\end{matrix}\)

De oplossing is \((a, b)=(3, -2)\text{.}\)

\(\begin{cases}5x-3y=1 \\ 3x-y=-5\end{cases}\) \(\begin{vmatrix}1 \\ 3\end{vmatrix}\) geeft \(\begin{cases}5x-3y=1 \\ 9x-3y=-15\end{cases}\)

Aftrekken geeft \(-4x=16\text{,}\) dus \(x=-4\text{.}\)

\(\begin{rcases}5x-3y=1 \\ x=-4\end{rcases}\begin{matrix}5⋅-4-3y=1 \\ -3y=21 \\ y=-7\end{matrix}\)

De oplossing is \((x, y)=(-4, -7)\text{.}\)

\(\begin{cases}3p+5q=1 \\ 4p+6q=-4\end{cases}\) \(\begin{vmatrix}6 \\ 5\end{vmatrix}\) geeft \(\begin{cases}18p+30q=6 \\ 20p+30q=-20\end{cases}\)

Aftrekken geeft \(-2p=26\text{,}\) dus \(p=-13\text{.}\)

\(\begin{rcases}3p+5q=1 \\ p=-13\end{rcases}\begin{matrix}3⋅-13+5q=1 \\ 5q=40 \\ q=8\end{matrix}\)

De oplossing is \((p, q)=(-13, 8)\text{.}\)