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

pages long, with each page containing

words. If Bill types an average of

words per minute, how many hours will it take him to finish the paper?

(A.)

(B.)

(C.)

(D.)

(E.)

Answer: (E.)

2.) If David paints at the rate of

houses per day, how many houses does he paint in

days, in terms of

and

?

Answer: