A train leaves its departure station with 6 coal cars, 12 iron cars, and 2 wood cars. Between each station, there are 6 miles, and it takes 25 minutes to travel between them. At each station, the train can deposit up to 2 coal cars, 3 iron cars, and 1 wood car. How many minutes will it take to deliver all the cars?
To deliver all the coal, you need to pass by 6 coal / 2 coal/station = 3 stations
To deliver all the iron, you need to pass by 12 iron / 3 iron/station = 4 stations
To deliver all the wood, you need to pass by 2 wood / 1 wood/station = 2 stations
So 4 stations are needed to deliver everything, so 4 stations * 25 minutes/station = 100 minutes are needed