39. If 4a = 5b and 5b = 7c, then 4a = 7c
[tex]\Rightarrow Transitive\text{ theorem}[/tex]
40. If m∠1 = 25, then m∠1 + 65 = 25 + 65
[tex]\Rightarrow Addition\text{ prop. of}[/tex]
41. If m∠1 + m∠2 =90, then ∠1 and ∠1 are complementary.
[tex]\Rightarrow Def\text{ of complementary }\angle^{\prime}s[/tex]
42. If ∠5 and ∠7 are supplementary and ∠7 and ∠2 are supplementary, ∠5 ≅ ∠2
[tex]\Rightarrow Supplements\text{ theorem}[/tex]
43. If ∠1 and ∠3 form a linear pair, then ∠1 and ∠3 are supplementary angles.
[tex]\Rightarrow Linear\text{ Pair Theorem}[/tex]
