Ineed to determine each angles measure. m 4

m 6

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
 
 M4 = 30
 M6 = 60