8) So remember the sum of all angles inside a triangle is equal to 180°. We first want to figure out the angle below the 110°.
A straight line is 180° so if we do 180 - 110 we get 70° therefore the angle below the 110° is 70°.
So we now know two angles in the triangle, 70° and 80°. Add these and we get 150°. Now we can determine the final angle (the one labelled (2x - 6)) which will be 30°.
So let’s make it into an equation:
2x - 6 = 30
Add 6 to both sides to isolate 2x:
2x = 36
Divide by 2 to get the value of x:
x = 18
10) Since the sum of all angles in a triangle is 180, and there are only 3 angles, we can determine A easily.
