Final answer:
To find the cost of each pen, we subtract the remaining amount from the initial amount to get the total spent on pens, then divide by the number of pens purchased. This reveals that each pen cost $4.
Step-by-step explanation:
The question asks us to calculate the cost of each pen given that a total of $23 was available and $3 was left after purchasing five pens. To find the cost of each pen, we subtract the final amount of money ($3) from the initial amount ($23) to determine the total spent on pens. This gives us $23 - $3 = $20 spent on pens.
Next, we divide the total spent on pens by the number of pens purchased to find the cost per pen. So, we get $20 divided by 5 pens, which equals to $4 per pen. Therefore, the cost of each pen is $4.