Hi!
The <u>Triangle Angle Sum Theorem</u> states that the sum of the interior angles in all triangles will always be 180 degrees.
We can set up an equation with the given information:
40 + (2x - 30) + (x + 20) = 180
Remove parentheses:
40 + 2x - 30 + x + 20 = 180
Combine like terms:
30 + 3x = 180
Subtract 30 from both sides:
3x = 150
Divide both sides by 3:
x = 50
Now, the problem wants us to solve for angle B.
Angle B is (2x - 30) degrees. We know the value of x, so we just have to substitute:
(2x - 30)
(2(50) - 30)
100 - 30
70
<u><em>Therefore, angle B is 70 degrees.</em></u>