There's So Many Selection!
You're in a stationary shop where a pen cost 50p and a pencil cost 15p. You want to buy a collection of pens and pencils and you have £25 (£1 is equivalent to 100p) to spend.
In how many ways can you spend exactly £25 pounds on buying those pens and pencils?
Details and Assumptions:
One way of spending exactly £25 pounds in that shop is buying only pens, that this spending £25 pounds on buying 50 pens. It is up to your personal choice on how many pens and how many pencils you want to buy, but before making a decision, you need to consider all possible combinations of set of pens and pencils you can buy, exactly in your budget.
You have no restriction on the minimum number of pens or pencils you should buy.
Another example of spending exactly £25 pounds on stationary collection is buying 20 pens and 100 pencils.