Answer:
Remember the Triangle Angle Sum theory which states that all angles of a triangle add up to 180˚. With this, make the following equation:
(3x-17) + (x + 40) + (2x - 5) = 180
Get rid of parenthesis
3x - 17 + x + 40 + 2x - 5 = 180
Group like terms:
3x + 2x + x + 40 - 17 - 5 = 180
Simplify
6x + 18 = 180
Subtract 18 from both sides.
6x + 18 - 18= 180 -18
6x= 162
Divide both sides by 6
6x/6= 162/6
x= 27