Question 137427
Distance(d) equals Rate(r) times Time(t) or d=rt;  r=d/t and t=d/r

distance first scientist travels=20t
distance second scientist travels=25t

Now we know that when the above two distances equal 90 mi, they will have lost contact, so our equation to solve is:

20t+25t=90
45t=90 divide both sides by 45
t=2 hrs--------------amount of time that elapses before they lose contact


Hope this helps---ptaylor