Is a relation a function if its graph intersects the y axis twice?

Jimmy can run 3.5 miles in 20 minutes. how far can ne run in one hour and ten minutes?

Ineed with question three. i don't understand how i'm supposed to achieve 3 marks.

The perimeter of ? cde is 55 cm. a rhombus dmfn is inscribed in this triangle so that vertices m, f, and n lie on the sides cd , ce , and de respectively. find cd and de if cf=8 cm and ef=12 cm. the answer is not cd=20 and de=15. i have tried that one, it does not work.