By geometrical inspection we have:
M4 = 30
Then the angle M6 can be determined from the fact that you have a rectangle triangle (345) that has an angle of 90 and another of 30. The missing angle measures:
180-90-30 = 60 = M3
Then to find M6 we have
M3 + 60 + M6 = 180
M6 = 180-60-M3
M6 = 180-60-60
M6 = 60
answer:
M4 = 30
M6 = 60
