Answer:
3rd option: 60 degrees
Step-by-step explanation:
We can see in the diagram that the angle on C is a supplementary angle, which means that the sum of 135 and internal angle will be equal to 180 degrees.
Let x be the internal angle,
Then
x+135 = 180
x = 180-135
x = 45 degrees
So now we know that two interior angles of the triangle.
Also we know that sum of all internal angles of triangle is 180 degrees.
Using the same postulate:
A+B+C = 180
75 + B + 45 = 180
120+B = 180
B = 180 - 120
B = 60 degrees
So,
third option is the correct answer ..
