Sam took traveled 8 hrs to his sisters house. The return trip took 7 hrs because the speed was 3 mi/hr faster. What was the Sam's speed each way?

I like to set up a chart for these kind of problems, they become very easy that way

D=r*t , Distance = rate*time

--------D------R-------T
.............................
trip #1 8x-----x------8
trip #2 7(x+3) x+3----7

the two distances are the same
----> 8x = 7(x+3)

etc

I knew the distance would be the same what I am having a problem with finding the the speed each way.