$\angle1$  and  $\angle6$  

 $\angle6$  and $\angle5$  

 $\angle7$  and $\angle8$  

 $\angle4$  and $\angle8$  

∠2 and ∠3

∠5 and ∠6

∠4 and ∠10

∠6 and ∠14

r is parallel to s by converse of Alternate Interior Angles Thm.

u is parallel to v by Converse of Corresponding Angles Thm

s is ⊥ u by Converse of Alternate Interior Angles Thm

v ⊥ r by Converse of Alternate Exterior Angles Thm

Substitution

Converse of Alternate Exterior Angles Theorem

Converse of Corresponding Angles Postulate

Converse of Same-side Interior Angles Theorem

$\angle4$ and $\angle8$

$\angle7$ and $\angle5$

$\angle1$ and $\angle2$

$\angle6$ and $\angle5$