.
To solve this problem (and many other similar problems, too), you do not need to know anything.
You need two things:
a) to read the condition attentively; to understand every word and to understand the meaning of the problem in whole
(usually, to get it, it is enough to read the problem two (2) or 3 (three) times);
b) a bit of common sense, that practically any human creation has to his (or her) 7 - 8 years.
In this problem, you are given a total amount of 500 pounds, and it is divided into 10 equal parts.
They ask you to evaluate the amount of each part in pounds.
At this point, a good style teaching requires me to stop.