Find the measure of each angle

Explanation

1. m(∠1) = 100^o because it is vertical angle to the angle with measure 100^o
2. m(∠2) = 80^o because it supplements angle ∠1.  So, 180^o - 100^o = 80^o
3. m(∠3) = 40^o .Since m(∠1) = 100^o, and the sum of m(∠1) + m(∠3) + m(∠4) = 180^o.  then m(∠3) + m(∠4) = 80^o.  Given that ∠3 ≅ ∠4, means their measures are equal, then both measures of ∠4 and ∠3 are 40^o
4. m(∠6) = 140^o because ∠6 and ∠5 are supplementary angles and m(∠5) = 40^o because ∠4 ≅ ∠5 and consequently m(∠5) = 40^o