Question

if ( mangle abd = 70^{circ} ) and ( mangle cbd = 30^{circ} ), then ( mangle abc = ?^{circ} )

Explanation:

Step1: Use angle addition formula

$$m\angle ABD=m\angle ABC + m\angle CBD$$

Step2: Solve for \(m\angle ABC\)

$$m\angle ABC=m\angle ABD - m\angle CBD$$
Substitute \(m\angle ABD = 70^{\circ}\) and \(m\angle CBD = 30^{\circ}\)
$$m\angle ABC=70^{\circ}-30^{\circ}$$
$$m\angle ABC = 40^{\circ}$$

Answer:

\(40\)