Who needs an anime gf?

The function models the number of accidents per 50 million miles driven as a function

Jonathan can type 20 documents in 40 minutes ,and susan can type it in 30 minutes and jack can type it in 24 minutes working together ,how much time will it is take them type the same document

Can someone me with this graph problem by the way i need to know the answers by today since this assignment is due ! !