Question 371958
A luxury liner left for a long voyage. When the ship was 360 miles from shore, a mail delivery helicopter, which could travel 10 times the speed of  the liner, took off after it.  How far from the shore will the helicopter be when it catches up with the liner. 


distance = rate * time
time = distance/rate
{{{x/R = (360 + x)/10R}}}
in time it takes for ship to go x miles,
the helicopter has to go 360 + x miles at 10 times the rate of the ship
R(360 + x) = 10Rx
360 + x = 10x
360 = 9x
40 = x
the helicopter will be 400 miles from the shore