Answer:
150
Explanation:
The exterior angle is equal to the sum of the opposite interior angles
<1 + <2 = <3
3x+11 + 3x+19 = 7x+10
Combine like terms
6x+30 = 7x+10
Subtract 6x from each side
6x -6x+30 = 7x-6x+10
30 = x+10
Subtract 10 from each side
30-10 = x+10-10
20 =x
We need to find angle 3
<3 = 7x+10
= 7(20)+10
= 140+10
= 150