Answer:
Substitution Property
Step-by-step explanation:
So we know that:

And we also know that:

And by using a specific property, we get that:

Essentially, we <em>substituted</em> B for A.
So, this is an example of the substitution property, where if two sides/angles are congruent, we can substitute them for each other.
Find slope as negative reciprocal of 2 => m=-1/2
y=mx + b
8=5(-1/2) +b
b=21/2
y= -1/2x +21/2
12 cubes of 1/4
Simply do 3 ><4=12 so 12 1/r cubes