15 plus what equals 0?

This is how to calculate "15 plus what equals 0?" In other words, 15 plus a number equals 0. What is that number? We start by converting this word problem into an equation where "what" is what we want to solve:

15 + what = 0

To solve this equation, we first add -15 to each side of the equal sign like this:

15 - 15 + what = 0 - 15

Then, we do the calculation to get the answer to "15 plus what equals 0?" as follows:

What = -15

The answer to "15 plus what equals 0?" is -15. You know this answer is correct because 15 plus -15 equals 0.

Plus What Equals Calculator
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