Question

what is the missing reason in step 3? statements reasons 1. $m\angle trv = 60^{circ}; m\angle trs=(4x)^{circ}$ 1. given 2. $\angle trs$ and $\angle trv$ are a linear pair 2. definition of linear pair 3. $m\angle trs + m\angle trv=180$ 3. ? 4. $60 + 4x=180$ 4. substitution property of equality 5. $4x = 120$ 5. subtraction property of equality 6. $x = 30$ 6. division property of equality substitution property of equality angle addition postulate subtraction property of equality addition property of equality

Explanation:

A linear pair of angles are adjacent angles that form a straight - line. The sum of the measures of angles in a linear pair is 180 degrees by the angle addition postulate. Since ∠TRS and ∠TRV are a linear pair (from step 2), we can say that the sum of their measures is 180 degrees.

Answer:

angle addition postulate