x=180 - (42+73)=180- 115
x=65 °
y=180 - 131
y=49°
z=x+y=65+49
z=114 °
w+49+(180-142)=180
w+49+38=180
w=180- (49+38)
w=180-87
w=93°
in the small triangle: the angle are t, y and ( I note the other angle) s
s=180-(42+w)
s=180-(42+93)
s=180-135
s=45°
t=180-(y+s)
t=180-(49+45)
t=180-94
t=86°