Originally Posted by

**Hellbent** Hi,

I just have some niggling doubts on solving these problems. I'm aware of the method of 'picking numbers', but I seek a more general understanding. Could someone explain to me how to solve these problems generally? Or how to think of them.

1.) Bill has to type a paper that is $\displaystyle p$ pages long, with each page containing $\displaystyle w$ words. If Bill types an average of $\displaystyle x$ words per minute, how many hours will it take him to finish the paper?

(A.) $\displaystyle 60wpx$

(B.) $\displaystyle \frac{wx}{60p}$

(C.) $\displaystyle \frac{60wp}{x}$

(D.) $\displaystyle \frac{wpx}{60}$

(E.) $\displaystyle \frac{wp}{60x}$

Answer: (E.) $\displaystyle \frac{wp}{60x}$

2.) If David paints at the rate of $\displaystyle h $ houses per day, how many houses does he paint in $\displaystyle d$ days, in terms of $\displaystyle h$ and $\displaystyle d$?

Answer: $\displaystyle hd$