You must use multiple different angle theorems in order to answer these questions.
In the first question, you use a Z angle theorem, where since the angles lie on a parallel line, angles a and b will equal to 180.
Angle a will equal 40 due to the alternate angles, and b will equal 140 since 180 - 40 = 140.
In the second question, you use corresponding angles. b will equal 72 since they are alternate angles and follow the Z angle theorem, and angle a = angle c. To get these, take 180 - angle b to get angle c, which is 180 - 72 = 108. Angle c = 108 and angle a = 108 since they are opposite angles.
In the third question, since everything takes place in a parallelogram, opposite angles will equal each other, thus angle b will equal 79. To get angle a, you do 180 - angle b or 79, 180 - 79 = 101. Angle a will equal 101.
*assume each number has a degree on them*
