i will give brainliest image below

Answer:
55°
Step-by-step explanation:
50+75=125. 180-125=55
55+90=145. 180-145=35
90-35=55
Angle ABC (B) is 55°
Method I used:
All lines need to add to 180° so I found the 3rd angle for C. Then I drew an imaginary line perpendicular to lines n and m that intersects line m at point B. The angles of that triangle need to add to 180° so I added 90° (right angle) with the 3rd angle of C (55°) then subtracted that value from 180 to get angle B. Then i found ABC (B).