What is the equation for 6/16

Alex took his brother to a birthday party. the party was scheduled to last for 1 and 3/4 hours but they stayed for 4/5 of an hour more. how long did she stay at the party?

90.0% complete a b c d e confirm last week, your delivery runs took 7 hours 12 minutes on monday, 6 hours 46 minutes on wednesday, and 6 hours 53 minutes on friday. what was your average time for a delivery run?

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.