What is the congruence theorem used to prove that the two triangles are congruent?

ASA

Step-by-step explanation

They have a congruent angle at the top of the triangle and they both have a right angle at the bottom. They share the same side, so this is ASA.

d. 9

step-by-step explanation:

54/12 = 4.5

sf = 4.5

so x = 2 · 4.5 = 9