The angles of an equilateral triangle all measure 60Υ, so ∠POQ=60∘. ∠3,∠4, and ∠POQ together form a straight angle, so we can write the following equation:​∠3+∠4+∠POQ=180∘∠3+∠4+60∘=180∘∠3+∠4=120∘​Note that we don't have to find the individual measurements of ∠3 and ∠4, just their sum. The correct answer is C, 120Υ.