Question 71530

Let x= number of hours 'till the motorboat and cruiser will be alongside

Distance(d)=rate(r) times time(t) or d=rt

rate for motorboat=9 mph
rate for cruiser=12 mph

When they have both traveled the same distance, they will be alongside

Distance motorboat travels=18+9x  (remember, motorboat had a 2 hour head start)
Distance cruiser travels=12x

So our equation to solve is:

18+9x=12x  subtract 9x from both sides
18+9x-9x=12x-9x collect like terms
18=3x  divide both sides by 3

x=6 hours  -----------------number of hours 'till they are alongside

CK

18+9(6)=12(6)
18+54=72
72=72


Hope this helps------ptaylor