Solve for x, where 3x + 8 = 80

In the diagram, the measure of angle 9 is 85° which angle must also measure 85°?

Which triangle congruence postulate or theorem justifies my claim that the steps i made using construction paper and scissors produce an isosceles triangle? was it sss, sas, asa, aas, or hl?

What is fraction that is equivalent to 3/8