Really need with numbers 78 & 80 you

Two airplanes start at the same place and travel in opposite directions,one at 395 miles per hour and the other at 422 miles per hour. how many hours will it take for the planes to be 2451 miles apart?

60 musicians applied for a job at a music school. 14 of the musicians play both guitar and drums, 28 play drums, 18 play the guitar. what is the probability that the applicant who gets the job plays drums or guitar?

Nicole purchased a container of cashews that weighs 5 kilograms. zion purchased a container of cashews that weighs 4,900 grams. how many more grams of cashews did nicole purchase?