For what values of $a$ and $b$ does the following system of equations have infinitely many solutions?<br> $\qquad \qquad \qquad ax+(b-1)y=5 ,\\ \qquad \qquad \qquad 2x-3y=-1.$

Question

$\begin{array}{1 1} a)\;a\;=\;-10\;;\;b\;=16 \;\\ b)\;a\;=\;10\;;\;b\;=\;-16\;\\ c)\;a\;=\;-10\;;b\;=\;-16 \\ d)\;a\;=\;10\;;\;b\;=\;16 \end{array}$