Which expression is equivalent to 5+5t+3t+?

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?

Anyone know? is appreciated! will mark brainliest if correct!

Determine the difference: 3.2 × 1010 – 1.1 × 1010. write your answer in scientific notation.