Find the missing number: 5 + ___ = 12.

To find the missing number in the equation 5 + ___ = 12, you're essentially determining what number can be added to 5 to result in 12.

Start by focusing on the given total, which is 12. To isolate the missing number, subtract 5 from 12:

12 - 5 = 7.

This calculation reveals that the missing number is 7, as adding it to 5 gives you 12:

5 + 7 = 12.

In the context of the choices provided, 7 is indeed the only number that satisfies the equation.