Use the photo and do the prove for #13 because i’m having a really hard time.

∠2 = ∠3 | Given

∠1 + ∠2 = 180 | Supplementary Angles Postule (If two angles are adjacent and                  ∠3 + ∠4 = 180|                                                        linear, they're supplementary)

∠1 + ∠2 = ∠3 + ∠4 | Transitive property

∠1 + ∠3 = ∠3 + ∠4 | Substitution property

∠1 = ∠4 | Subtraction Property

∠2 = ∠3 | Supplementary Congruent Theorem

the answer would be 150 books

step-by-step explanation:

if you divide 300 by 2 you will get 150