[tex] \sf 3a. \quad \frak{7x + 5(x - 1) = - 5 + 12x} \\ \\ : \implies \frak{7x + 5x - 5 = - 5 + 12x} \\ \\ : \implies \frak{7x + 5x - 5 = - 5 + 12x} \\ \\ : \implies \frak{12x - \cancel5 + \cancel5=12x} \\ \\ : \implies \frak{ \cancel{12x} - \cancel{12x} = 0} \\ \\ \star \qquad \underline{ \blue{\frak{x = undefined}}}[/tex]
[tex] \sf3b. \quad \frak{6(y - 5) = 2(10 + 3y)} \\ \\ \dashrightarrow \frak{6(y - 5) = 2(10 + 3y)} \\ \\ \dashrightarrow \frak{6y - 30= 20 + 6y} \\ \\ \dashrightarrow \frak{0y = 50} \\ \\ \star \qquad \underline{ \blue{\frak{y = undefined}}}[/tex]
