If i came to work at 3: 30 p. m. and left at 12: 15 p. m. midnight how many hours did i work

Can someone me and do the problem plz so i can understand it more better

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

The equatorial radius of earth is approximately 6 × 10^3 km, while the equatorial radius of saturn is approximately 6 × 10^4 km. which of the following is true? a. the equatorial radius of saturn is approximately one hundred times that of earth. b. the equatorial radius of saturn is approximately ten times that of earth. c. the equatorial radius of earth is approximately one hundred times that of saturn. d. the equatorial radius of earth is approximately ten times that of saturn.