1: yes solve the equation 3.14• the diameter
2:yes work backwards dividing pie from the circumference
21 = x + 6x
Solve that in order to answer your problem.
Well if we have two angles, LMT and TMN, that make up LMN, then the sum of LMT and TMN should equal LMN.
144 + 23 = 167 degrees.
Hope this helps!