Question

1. if (mangle abd = 48^{circ}) and (mangle dbc = 78^{circ}), find (mangle abc).

Explanation:

Step1: Identify angle - addition relationship

Since $\angle ABC=\angle ABD+\angle DBC$.

Step2: Substitute given angle measures

We know that $\angle ABD = 48^{\circ}$ and $\angle DBC=78^{\circ}$, so $m\angle ABC=48^{\circ}+78^{\circ}$.

Step3: Calculate the sum

$48 + 78=126$. So $m\angle ABC = 126^{\circ}$.

Answer:

$126^{\circ}$