Min's hose can pump 21 gallons of water every hour. how many gallons of water will he fill up if he runs the hose for 2/3 of an hour?

Ben frank is an electrician who installs lighting fixtures. he charges (in dollars) his clients 15h+40f15h+40f where hh is the number of hours worked and ff is the number of fixtures installed. how much does ben frank charge when he works 77 hours and installs 99 fixtures?