Answer:
see below
Step-by-step explanation:
The sum of the interior angles is 180
<1 + <2 + <4 = 180
<1 + 31+ <4 = 180
<1 + <4 = 180-31
<1 + <4 = 149
<2 + <3 = 180 because it forms a straight line
31 + <3 = 180
<3 = 180-31
<3 = 149
Setting theses equal (since they are both equal to 149)
<1 + <4 = <3
The exterior angle is equal to the sum of the opposite interior angles
