Question

# Angles A and B are supplementary.If mangle A= 78° what is mangle B?

Transformation properties

Angles A and B are supplementary.
If $$\displaystyle{m}\angle{A}={78}°$$ what is $${m}\angle{B}$$

The measures of supplementary angles add up to $$180^{\circ}$$. So if $$\displaystyle{m}\angle{A}=78^{\circ}$$, then the measure of angle B must be $$\displaystyle{m}\angle{B}=180^{\circ}-{m}\angle{A}={180}^{\circ}-{78}^{\circ}={102}^{\circ}$$