3 plus what equals 12?

This is how to calculate "3 plus what equals 12?" In other words, 3 plus a number equals 12. What is that number? We start by converting this word problem into an equation where "what" is what we want to solve:

3 + what = 12

To solve this equation, we first add -3 to each side of the equal sign like this:

3 - 3 + what = 12 - 3

Then, we do the calculation to get the answer to "3 plus what equals 12?" as follows:

What = 9

The answer to "3 plus what equals 12?" is 9. You know this answer is correct because 3 plus 9 equals 12.

Plus What Equals Calculator
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