Question

Angles A and B are adjacent on a straight line. Angle A has a measure of (2r +20) and angle B has a measure of 130.. What is the measure of r?

Answer 1

When two angles are adjacent on a straight line, then the sum of the two angles equals 180 (that is sum of angles on a straight line). Therefore;

`\begin{gathered} (2r+20)+130=180 \\ \text{Subtract 130 from both sides and you'll have} \\ 2r+20=50 \\ \text{Subtract 20 from both sides and you'll have} \\ 2r=30 \\ \text{Divide both sides by 2 and you'll have} \\ r=15 \end{gathered}`

The measure of r is 15