Question

2.3 determine the value of m. (give a reason for your answer)
statement
reason
section b total: /22

Explanation:

Step1: Recall angle - sum property

The sum of angles on a straight - line is $180^{\circ}$.

Step2: Set up the equation

$70^{\circ}+80^{\circ}+(m + 10^{\circ})=180^{\circ}$.

Step3: Simplify the left - hand side

$160^{\circ}+m=180^{\circ}$.

Step4: Solve for m

$m=180^{\circ}-160^{\circ}=20^{\circ}$.

Answer:

$m = 20^{\circ}$