I'll pick it up from there rupert.
After a long and hard journey around the world, Tasmania Jones starts to crave for his wife Victoria Jones.
So, Tasmania books a flight back home to see his wife again for sex.
Unfortunately, Tasmania's lack of sex has let him down and he is only able to last for a very limited time. Thus, his wife has threatened to leave him if he doesn't improve.
His duration can be modelled by the following formula: <formula here> where < indenpendant variable here> stands for <measurement here> and <variable here> stands for <measurement 2 here>
Victoria Jones clearly states that he should last at least for 15 mins otherwise he sees the divorce papers on Monday.
Solve for <independant variable here> which tells Tasmania Jones how many hours of practice he needs so that he is able to last for at least 15 mins.
etc.