Answer:
m<ABC = 41
m<DBC = 39
Step-by-step explanation:
m<ABC + m<DBC = m<ABD
m<ABC = 7x - 8
m<DBC = 5x + 4
m<ABD = 80
7x - 8 + 5x + 4 = 80
12x - 4 = 80
12x = 84
x = 7
m<ABC = 7x - 8 = 7(7) - 8 = 49 - 8 = 41
m<DBC = 5x + 4 = 5(7) + 4 = 35 + 4 = 39
m<ABC = 41
m<DBC = 39
