Developing proof fill in the blanks to complete this proof of theorem 2-4.
all right angles are congruent.
given: x and y are right angles.
prove: 2x = 2y
proof: x and a. ? are right angles because it is given.
by the definition of b. ? ,m x = 90 and m2y = 90.
by the transitive property of equality, m 2x = c. ? .
because angles of equal measure are congruent, d. ? .