[tex]\displaystyle \\
8a) ~~\alpha = \frac{360-144}{2} = \frac{216}{2} = \boxed{108^o} \\ \\
8b) ~~\alpha = 180-110 = \boxed{70^o} \\
8c) ~~\alpha = 180 - (\alpha - 40) \\
\alpha = 180 - \alpha + 40 \\
2\alpha = 180 + 40 \\ \\
\alpha = \frac{180 + 40}{2} = \frac{220}{2} = \boxed{110^o} \\ \\
8d) ~~\alpha = 180 - (\alpha + 30) \\
\alpha = 180 - \alpha - 30 \\
2\alpha = 180 - 30 \\ \\
\alpha = \frac{180 - 30}{2} = \frac{150}{2} = \boxed{75^o} [/tex]
