In ΔBCD, start overline, B, D, end overline
BD
is extended through point D to point E, m, angle, B, C, D, equals, left bracket, 3, x, plus, 14, right bracket, degreesm∠BCD=(3x+14)
∘
, m, angle, C, D, E, equals, left bracket, 9, x, minus, 17, right bracket, degreesm∠CDE=(9x−17)
∘
, and m, angle, D, B, C, equals, left bracket, 3, x, plus, 20, right bracket, degreesm∠DBC=(3x+20)
∘
. Find m, angle, D, B, C, .m∠DBC.