Answer:
m < DBC = 51
Step-by-step explanation:
Looking at the picture, we know <ABD and <DBC make up <ABC. Knowing this, we can set up an equation like so, plug in the known values, and solve to find m<DBC:
[tex]m<ABC = m<ABD + m<DBC\\122 = 71 + m<DBC\\m<DBC = 122 - 71\\m<DBC = 51[/tex]
