[b][size=150]D is in the interior of ∠ABC[/size][/b]
[b][size=150]m∠ABD + m∠DBC = m∠ABC[/size][/b]
[b][size=150]If D is in the interior of ∠ABC , m∠ABC=123° and m∠ABD=55°. Find m∠CBD[/size][/b]
[b][size=150]If m∠ABD=130° and m∠ABC=50°. Find m∠DBC[/size][/b]