In taking inventory, Devin finds he has 3 ink cartridges and needs 10. How many ink cartridges does he need to order?

To determine how many ink cartridges Devin needs to order, we start by identifying what he currently has and what he requires. Devin currently has 3 ink cartridges and needs a total of 10.

To find out how many more cartridges he needs, we perform a simple subtraction:

10 (the total needed) - 3 (the current number) = 7.

This calculation shows that Devin needs to order 7 additional ink cartridges to meet his requirement.

In summary, the correct answer reflects the difference between the total required and what is already available.