Question

Justify each statement with a property from algebra or property of congruence.

If$m\angle A+m\angle B+50=180$then $m\angle A+m\angle B=130$.

Short answer

From the property of Algebra, it is proved that $m\angle A+m\angle B=130$.

Step-by-step solution

Step 1. Description of step.

The sum of measures of all the interior angles of a triangle is 180.

$m\angle A+m\angle B+50=180$

Step 2. Apply subtraction property of algebra.

If $p=q$and $r=s$ then $p-r=q-s$.

Step 3. Description of step.

Subtract 50 from both sides of the $m\angle A+m\angle B+50=180$.

$\begin{array}{c}m\angle A+m\angle B+50-50=180-50\\ m\angle A+m\angle B=130\end{array}$

Therefore, it is proved that $m\angle A+m\angle B=130$.