`a,`
`-45 : 5 . (-3 - 2x) = 3`
`=> -9 . (-3 - 2x) = 3`
`=> -3 - 2x = 3 : (-9)`
`=> -3 - 2x = (-1)/3`
`=> 2x = -3 - (-1)/3`
`=> 2x = (-8)/3`
`=> x = (-4)/3`
`b,`
`x . (x + 7) = 0`
`=>` \(\left[ \begin{array}{l}x=0\\x + 7 = 0\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=0\\x=-7\end{array} \right.\)
`c,`
`(x + 12) . (x - 3) = 0`
`=>` \(\left[ \begin{array}{l}x + 12 = 0\\x -3 = 0\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=-12\\x=3\end{array} \right.\)
