Since we're doing fun with math...If assembly line a takes 3 minutes to bind and package 1 case of notebooks...
and assembly line b -which is newer- takes 150 seconds to do the same work, then how long will the two assembly lines have to run together to fill a large order for a retail chain that wants 1400 cases of notebooks?
Here's the solution: 3 minutes per case implies 20 cases per hour. 150 seconds is also 2.5 minutes, which suggests 24 cases per hour, or 44 cases per hour of production with both lines running together.
1400 cases in the order / 44 cases per hour of production = 31.82 hours.