To solve this problem, you have to know that the measure of all the angles of a triangle is equal to 180 degrees.
Let's add each angle together and set them equal to 180 degrees.
180 degrees = 3x + 2x + 1 + x + 5
Combine like terms
180 degrees = 6x + 6
Subtract 6 from both sides
174 degrees = 6x
Divide both sides by 6
29 = x
We know that angle A = 3x = 3(29) = 87 degrees.
