Answer
a) $40^{\circ}$
b) $90^{\circ}$
Work Step by Step
To use the protractor, we subtract the smaller angle at one end of the protractor from the larger angle at the protractor. Doing this, we find:
Case A:
$$\angle1=40^{\circ}-0^{\circ} \\ \angle1=40^{\circ}$$
Case B:
$$ \angle3 = 130^{\circ}-40^{\circ} \\ \angle3 = 90^{\circ}$$
