Z + Y = a right angle so need to equal 90 degrees:
Find Z & Y:
2b + 6 + 3b -1 = 90
5b +5 = 90
5b = 85
b = 85/5
b = 17
Z = 2(17) +6 = 34+6 = 40 degrees
Y = 3(17) - 1 = 51 - 1 = 50 degrees
Y & W make a straight line so need to equal 180:
W = 180 - 50 = 130 degrees.
Z & X make a straight line so need to equal 180:
X = 180 - 40 = 140 degree.