Find the measure of the missing angles

b=80

c=80

Step-by-step explanation:

the angle opposite to the 100 degree angle is congruent to it

same goes for b and c

so far we have 2 angles that measure 100 degrees 100+100=200

the sum of the 4 angles is 360

360-200=160

160/2=80=b=c

b.an increase in a causes b to decrease