pradeepkaushal9518 wrote:aaron will jog from home at x miles per hour and then walk back home by the same route at y miles per hour. how many miles from home can aaron jog so that he spends a total of t hours jogging and walking?
a.xt/y
b.(x+y)/xy
c.xyt/x+y
d.x+Y+t/xy
e.y+t/x-t/y
Pradeep,
There are already two very good methods explained above, which will guide you to the correct answer.
But, if at all, in the exams you are not able to recall any of the methods, your logic will come in handy.
One more method :
You need Miles in the answer. Now, look at the options and just put the units of X, Y, and T. After cancellation, try to figure out which one gives Miles in the end. That's it!
For e.g., let's take option A.
(X * T)/ Y OR
(Miles/hr) * (hr) / (Miles/hr) = hr. Nopes! eliminated!
Similarly, option B :
(X+Y)/XY= (Miles/hr) / (Miles/hr)^2 = hr/Miles. Nopes! eliminated.
You'll find that the expression in C alone has the unit as Miles.

Options D and E are not even valid.
You've got your answer!