6 plus what equals 15?

This is how to calculate "6 plus what equals 15?" In other words, 6 plus a number equals 15. What is that number? We start by converting this word problem into an equation where "what" is what we want to solve:

6 + what = 15

To solve this equation, we first add -6 to each side of the equal sign like this:

6 - 6 + what = 15 - 6

Then, we do the calculation to get the answer to "6 plus what equals 15?" as follows:

What = 9

The answer to "6 plus what equals 15?" is 9. You know this answer is correct because 6 plus 9 equals 15.

Plus What Equals Calculator
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