I'm guessing d b are equal and a and c are equal or I don't think we would be able to solve so going on that if angle d is 57 angle b must also be 57 A parallelegram has angles that add up to 360 So 360= 57+57+2c Solve 360=114+2c -114 both sides 246=2c ÷2 both sides 123=c
