Answer:
Below in bold.
Step-by-step explanation:
C1 = 180 - C2
= 180 - (170-2x)
= 10 + 2x
So B3 = 10+2x (alternate angles).
and B2 = 90 - B3
= 90 - (10 + 2x)
= 80 - 2x.
