# Math Help - word problem help please!

1. ## word problem help please!

hi, i really don't understand math problems so if anyone could help it would be greatly appreciated!.

okay,
A person traveled 120 miles in one direction. The return trip was accomplished at double the speed and took 3 hours less time. Find the speed going.

2. Originally Posted by heather_meaghan
hi, i really don't understand math problems so if anyone could help it would be greatly appreciated!.

okay,
A person traveled 120 miles in one direction. The return trip was accomplished at double the speed and took 3 hours less time. Find the speed going.
Remember $\mbox{Speed } = \frac {\mbox{Distance}}{\mbox{Time}}$

Let $s$ and $t$ be the speed and time, respectively, for the first trip.

Thus, for the second trip, the speed and time is $2s$ and $(t - 3)$ respectively.

But the distances are the same!

and $\mbox{Time } = \frac {\mbox{Distance}}{ \mbox {Speed}}$

thus, for the first trip, $t = \frac {120}s$

for the return trip, $t - 3 = \frac {120}{2s} \implies t = \frac {120}{2s} + 3$

now equate the t's

$\frac {120}s = \frac {120}{2s} + 3$

Now solve for s