Question

find the measure of ∠tbf.

Explanation:

Step1: Identify vertical - angle relationship

Vertical angles are equal. $\angle TBF$ and the given $121^{\circ}$ angle are vertical angles.

Step2: Determine the measure of $\angle TBF$

Since vertical angles are congruent, $\angle TBF = 121^{\circ}$.

Answer:

$121^{\circ}$