90 plus what equals 10?

This is how to calculate "90 plus what equals 10?" In other words, 90 plus a number equals 10. What is that number? We start by converting this word problem into an equation where "what" is what we want to solve:

90 + what = 10

To solve this equation, we first add -90 to each side of the equal sign like this:

90 - 90 + what = 10 - 90

Then, we do the calculation to get the answer to "90 plus what equals 10?" as follows:

What = -80

The answer to "90 plus what equals 10?" is -80. You know this answer is correct because 90 plus -80 equals 10.

Plus What Equals Calculator
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