ANSWER
The substitution property of equality.
EXPLANATION
We know that:

and that

Since x=5 or 5=x , we can substitute x for 5 wherever we see x in the given equation.
When we do that, we obtain;

This is what we refer to as the substitution property of equality.
Answer:
45.9318
Step-by-step explanation:
The answer is 37. Hope this helps!
(25-y) ^2-y^2=25
y=12
x=25-12
x=13
(13,12)