What is the common difference between the elements of the arithmetic sequence below? –18, –22.5, –27, –31.5, –36

In trapezoid klmn, kj=19.2 and jm=22.5. identify ln.

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 the value of x in the diagram below?