Simple math is hard

[CrAz3D]

Problem 1:
A man travels a certain distance at 60 miles per hour and returns over the same road at 40 miles per hour.  What is his average rate for the round trip in miles per hour?
Answer is 48 (says the book) but how?


Problem 2:
If the profit gained on the sale of an article is 10% of the selling price, and the original cost of the srticle is $12.60, the article must be marked for?
Answer is $14.00 (says the book) but how?

[Maddox]

1) v = 2d / [(d / 60) + (d / 40)]
solve the equation, your d's will cancel and you will get your answer.

2) p(1-.10) = 12.60
solve the equation for p, that will get you your answer.

[CrAz3D]

1) v = 2d / [(d / 60) + (d / 40)]
solve the equation, your d's will cancel and you will get your answer.

d is distance? 
Ok, much thanks Maddox