Question

(c) find m∠abc.

Explanation:

Step1: Observe the angle relationship

The angle $\angle DBC = 120.96^{\circ}$ and $\angle DBA=90^{\circ}$. We know that $\angle DBC=\angle DBA + \angle ABC$.

Step2: Solve for $\angle ABC$

$\angle ABC=\angle DBC-\angle DBA$. Substitute $\angle DBC = 120.96^{\circ}$ and $\angle DBA = 90^{\circ}$ into the formula. So, $\angle ABC=120.96^{\circ}- 90^{\circ}=30.96^{\circ}$.

Answer:

$30.96^{\circ}$