The number of gallons of coffee a mathematician drinks on any given day is inversely proportional to how much sleep he gets the
night before. On Monday, he got 9 hours of sleep and drank 2 gallons of coffee. On Tuesday, he got 6 hours of sleep. How many gallons of coffee did he drink?
Given that y varies inversely with x, then: y=k/x where k is the constant of proportionality: k=yx hence, given that x=28 when y=2, then the value of k will be: k=28×2 k=56
