The two decide to work together on a lit theme packet, each writing part of a round, starting at the same time.
Inform players that their answer should be given in hours.  Working by himself, Trygve Meade can write a round of literature questions in four hours. Donald Taylor, working solo, could produce a round of lit questions in three hours. The two decide to work together on a lit theme packet, each writing part of a round, starting at the same time. If their writing rate is unchanged, how long does it take for the two to write a lit theme packet? After one hour of working in tandem, 1/3 plus 1/4 is done. For ten points, what is the reciprocal of the sum of 1/3 and 1/4?
Inform players that their answer should be given in hours.  
{12/7} (accept 1 5/7 hours)