Answer:
m∠EBC=34°
Explanation:
we know that
m∠DBC=m∠DBE+m∠EBC
see the attached figure to better understand the problem
substitute the given values in the formula and solve for x

Find the measure of angle EBC
m∠EBC=(3x+13)°
substitute the value of x
m∠EBC=(3(7)+13)°
m∠EBC=(21+13)°
m∠EBC=34°