Answer:
85°
To get this,know that the total angle of triangle is 180°[(n-2)180] n=number of sides.Total angle on a straight line is 180°.
There are 3 angle you need to calculate.
Upper angle:180-133=47°
Right angle:180-142=38°
Left angle:180°-47°-38°=95°
n+95°=180°
n=180°-95°=85°
