Answer:
x = 50
∠B = 70°
Explanation:
The sum of interior angles in a triangle is equal to 180 so to find the value of x we can use the following equation:
40 + x + 20 + 2x - 30 = 180 add like terms
3x + 30 = 180 subtract 30 from both sides
3x = 150 divide both sides by 3
x = 50 to find the angle measures replace x with 50 in each expression.
∠B = 2×50 - 30
∠B = 70°