Concept:Use angle-sum properties of triangles and supplementary angles on straight lines.Explanation:Since STUV is a straight line, ∠TUW=180∘−110∘=70∘.From the straight lines in the diagram, ∠XUT=70∘ and ∠TXU=∠UXY=40∘.In △XTU, ∠XTU=180∘−70∘−40∘=70∘.At T, ∠YTS and ∠XTU lie on a straight line, so ∠YTS=180∘−70∘=110∘.In △STY, ∠SYT=180∘−40∘−110∘=30∘.Since S, Y, and W lie on a straight line, ∠SYT+∠TYW=180∘.Hence ∠TYW=180∘−30∘=150∘.Answer:∠TYW=150∘, so the correct option is A.
