Balance Addition Equations - Within 100

Consider the equation:

35 + 12 = __ + 40

Let's identify the missing number that makes the equation true.

To find the missing number, first we need to add 35 + 12:

35 + 12   =     ? + 40

47            =     ? + 40

Now, let’s look for the number which when added to 40 gives 47.

47 = 7 + 40

35 + 12 = 7 + 40

So, the missing number is 7.