Answer:
x = 50
Explanation:
Creating an equation to solve for x using basic geometry rules
Angles in a triangle always add up to 180 degrees.
This means that x + 2x - 10 + 40 must be equal to 180
Solving for x algebraically
x + 2x - 10 + 40 = 180
==> combine like terms
3x + 30 = 180
==> subtract 30 from both sides
3x = 150
==> divide both sides by 3
x = 50
Checking our answer by plugging in x and seeing if the equation created is true
x + 2x - 10 + 40 = 180
==> plug in x = 50
50 + 2(50) - 10 + 40 = 180
==> multiply 2 and 50
50 + 100 - 10 + 40 = 180
==> combine like terms
180 = 180 ( this is true so the answer is indeed x = 50 )