Basic Mathematics
# Angles and Lines

$l \parallel m$, and $\angle a = 21^\circ$, what is the measure of $\angle b$ in degrees?

If$ABCD$ has $\angle D = \color{#3D99F6}{x}$ and $\angle A = \color{#20A900}{2x + 12^\circ}$. What is the measure of $\angle D$?

Trapezoid$l \parallel m,$ what is the measure of $\color{#3D99F6}{\angle A}+\color{#20A900}{\angle B} ?$

In the above diagram, if