Check the picture below, with that template in mind
[tex]y = \stackrel{A}{2}|\stackrel{B}{1}x+\stackrel{C}{4}|\stackrel{D}{-3}\qquad \begin{cases} A=2~~,~~B=1\\ \qquad \textit{shrinks by a factor of 2}\\ B=1~~,~~C=4\\ \qquad \textit{horizontal leftwards shift by }\frac{4}{1}=4\\ D=-3\\ \qquad \textit{vertical downwards shift by 3} \end{cases}[/tex]