Answer:
+15
Step-by-step explanation:
An increase is generally regarded as being positive. If units are dollars, an increase of $15 can be represented by the integer +15.
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Additional comment
If units are dimes, then the number would be +150. So, you see, the units are important to know.
It also depends on what is increasing and what is being represented by the integer. If it is an increase in debt, then the change in net worth might be -15.
