Need to find the real number.

Question

Someone performed a trade of 20,000 less than it made, this caused a negative trade balance.

To represent the quanity as a real number when I know that a positive real number names the points to the right of 0 on the number line and negative towards the left of 0.
This question seems to lead me to a negative response. Not knowing the orginal ballance confuses me, proberly when it should not.

I'm lost??
I know that when subtracting real numbers signs change and negative numbers become positive, example: a - b = a + (-b)
Therefore, X - 20,000 = X + (-20,000) =

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