## Prealgebra (7th Edition)

$\angle a+\angle b= 47^{\circ}+133^{\circ}=180^{\circ}$ $\angle a+\angle d= 47^{\circ}+133^{\circ}=180^{\circ}$ $\angle c+\angle b= 47^{\circ}+133^{\circ}=180^{\circ}$ $\angle c+\angle d= 47^{\circ}+133^{\circ}=180^{\circ}$
Two angles are supplementary if they add up to $180^{\circ}$, which is a straight angle. In the picture, there are 4 different straight angles, therefore there will be 4 different pairs of supplementary angles. $\angle a+\angle b= 47^{\circ}+133^{\circ}=180^{\circ}$ $\angle a+\angle d= 47^{\circ}+133^{\circ}=180^{\circ}$ $\angle c+\angle b= 47^{\circ}+133^{\circ}=180^{\circ}$ $\angle c+\angle d= 47^{\circ}+133^{\circ}=180^{\circ}$