Use the diagram to complete the proof that angle ACD = 130 by filling in the missing steps.

Question

A. Angle ACB + angle BCE = 180.      A. 

B. 5x + 9x + 40 = 180.                     B. ?

c. 14x + 40 = 180.              C. Combine like terms

d. 14x = 140.                     D. ?

e. X = 10.              E. Division of property equality

f. AngleBCE=9(10)+40=130    F. Substitution property 

G. Angle BCE=ACD.            G. ?

h. Angle ACD=130.          H. Substitution property 

Answer 1

a) Guessing a bit here, but seems like a combination of Angle Addition Postulate and definition of a Linear Pair.

 

b)  Substitution.

c) Simplify or combine like terms.

d) Subtraction of Equality.

e) Division of Equality.

f) Substitution

g)Vertical Angles Congruence Theorem + Definition of Congruent Angles?

h) Substitution.

 

Please note the ? are only due to the lack of a picture.