p.393 in FOM (looking at digital copy) The question states: If Roger took 2 hours to walk to a store that is 3 miles away, and then ran home along the same path in 1 hour, what was Roger's average speed, in miles per hour, for the round trip? I did this by taking the average of the two rates. On the...

I understand that "per" usually means division and this usually works out in the problems I work through. However I see that this doesn't work sometimes and I'm not sure why. For example in the Word Problems guide, Chapter 2, p. 22, there's a question: "Machine X produces cartons at a...

I wouldn't say I made an equation without knowing what it means, but now I see I was missing the T component in RT=D. I was solving for the time variable in the denominator of the R component. Thanks for posting.