Answer:
BCF = 140°
See attached image.
m<BCF=140°
Step-by-step explanation:
first find m<BCD
m<BCD=180-50-90
m<BCD=40°.
to find m<BCF, we can do 180-m<BCD, since m<BCD and m<BCF add up to 180° (they form a straight angle)
180-m<BCD=m<BCF
180-40=m<BCF
