If you're describing a time, then it has to have a unit of time. We have no idea how much gas you're talking about, so second, minute, and hour are all possibilities.
I believe it's 7.5 but I could be wrong.
I do not understand ur language I speak English very well sorry I can't help you with your homework
25d^2-30d-35d+42=25d^2-65d+42.