$\angle A$ and $\angle B$ are supplementary angles. If $\angle A : \angle B = 3 : 7$,then $\angle B = \dots$ (in $^o$)

In the given figure,if $AB \parallel CD$,$\angle PCD = 130^{\circ}$ and $\angle PBA = 140^{\circ}$,then find $\angle BPC$. (in $^{\circ}$)

Prove that the sum of the three angles of a triangle is $180^{\circ}$.

$\angle ACD$ is an exterior angle of $\Delta ABC$. If $\angle A = 70^{\circ}$ and $\angle B = 40^{\circ}$ in $\Delta ABC$,then find $\angle ACD$. (in $^{\circ}$)

$A$ straight angle has measure......... (in $^{\circ}$)

In $\Delta ABC$,if $\angle A = \angle B = \angle C$,then $\angle B = \dots$ (in $^{\circ}$)