Question

if m∠abd = 70° and m∠cbd = 30° then m∠abc = ?

Explanation:

Step1: Identify angle - relationship

We know that $\angle ABD=\angle ABC+\angle CBD$.

Step2: Solve for $\angle ABC$

By re - arranging the formula, we get $\angle ABC=\angle ABD - \angle CBD$.
Substitute $\angle ABD = 70^{\circ}$ and $\angle CBD=30^{\circ}$ into the formula: $\angle ABC=70^{\circ}-30^{\circ}$.

Answer:

$40$