Rebecca M. answered 09/17/19
Math tutor for 4 yrs at a charter high school; 1.5 yrs at Job Corp
Angles are named by listing a point on a ray of the angle, the vertex and a point on the other ray. Thus the angle AOC has a point in the middle called B. Angle AOB is adjacent to Angle BOC. By the angle addition postulate add the two expressions together to have the total. Substitution in: 3x + 1 + 7x+ 4 = 105. Combining terms 10x + 5 = 105.
Subtract 5 from both sides: 10x = 100
Divide by 10: x = 10.
Substitute x back in for measurement of angle AOB: 3 ( 10) + 1 = 30 + 1 or 31