Solve using suitable property: (-15) x 8 + (-15) x 4

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 the expression 9+n/3-6 when n = 12? 1. 5. 7. 12.

The length of the line segment joining the midpoints of sides ab and bc of the parallelogram abcd is 10. find the length of diagnol ac