Answer:
77º
Step-by-step explanation:
The picture shows us a parallelogram (AB║CD and AD║BC)
We know that in a parallelogram the inside angles sum up 360º. We also know that two adjacent angles in a parallelogram sum up 180º.
Therefore, we would have that ∠ABC + ∠BCD = 180
We solve for ∠BCD:
∠ABC + ∠BCD = 180
103 + ∠BCD = 180
∠BCD = 180 - 103
∠BCD = 77
Therefore, we have that ∠BCD = 77º
