To find the magnitude of the resultant of 60N at 90 degrees, 80N at 120 degrees and 100 N at 270 degree, you will just minus 180 degrees to 180 degrees since the remaining angle is the resultant velocity of the unmeasured side of the angle. Since there is a given of 30 degrees, then 180 degrees-30 degree = 150 degrees. Th magnitude is Ncos150 where N=squareroot of A^2+B^2 and the answer is 128.06
SO magnitude= 128.06cos150
=110.91
or 111
