Question

if ( mangle abd = 61^{circ} ) and ( mangle dbc = 59^{circ} ), then ( mangle abc = ) ?

Explanation:

Step1: Use angle addition postulate

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

Step2: Substitute given values

$$m\angle ABC=61^{\circ}+59^{\circ}$$

Step3: Calculate sum

$$m\angle ABC = 120^{\circ}$$

Answer:

120