39. If 4a = 5b and 5b = 7c, then 4a = 7c

40. If m∠1 = 25, then m∠1 + 65 = 25 + 65

41. If m∠1 + m∠2 =90, then ∠1 and ∠1 are complementary.
![\Rightarrow Def\text{ of complementary }\angle^(\prime)s]()
42. If ∠5 and ∠7 are supplementary and ∠7 and ∠2 are supplementary, ∠5 ≅ ∠2

43. If ∠1 and ∠3 form a linear pair, then ∠1 and ∠3 are supplementary angles.
