*see attached photo* What is step 10 in this proof?

A. Statement Point P lies on line CD

Reason: The coordinates of P satisfy the equation of line C’D’

B. Statement: All three lines share point P.

Reason: Definition of midpoint

C. Statement: Two of the three medians share point P.

Reason: Using point slope formula

D. Statement: line A'E' and line A'E' are concurrent

Reason: Definition of concurrence

E. Statement Point P lies on line A'E' and line A'E.

Reason: Algebra