The right answer is 2p + 9 = 25
According to this problem, we know:
- p represents the number of pens.
- There are 25 writing utensils in a container in all.
- There are pens and pencils in the container in all.
The statement there are nine more pencils than pens in the container can be written as follows:
(1) P = p + 9
where:
P: Number of pencils
p: Number of pens
There are 25 writing utensils in the container in all, therefore:
(2) p + P = 25
Matching these two equations, we have:
(1) P = p + 9
(2) p + P = 25
Substituting (1) in (2):
p + (p+9) = 25
∴ 2p + 9 = 25
Therefore:
2p = 16 ∴ p = 8
and P
P = p + 9 ∴ P = 17
Finally:
There are 8 pens and 17 pencils in the container.
