Question B.2: Solve the two simultaneous equations (1) 5x + y = -8 (2) 2x ...

From (2), x = y + 2. Substitution of this equation into (1) gives

\begin{aligned}5(y+2)+y &=-8 \\6 y &=-18 \\y &=-3 \\x &=y+2=-1\end{aligned}

Alternative Solution Multiply each term in (1) by the factor 2 and add the result to (2):

\begin{gathered}10 x+2 y=-16 \\2 x-2 y=4\\\hline\end{gathered}

\begin{aligned}12 x \quad &=-12 \\x &=-1 \\y &=x-2=-3\end{aligned}