Daniela ha hecho una mala inversión y diariamente pierde $3.000. Esta pérdida la podemos representar por un número negativo es decir como: -3.000.
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the entire expression should be subtracted from 30. to subtract the quantity, distribute the negative sign, which changes the signs on the terms. so, the –2 changes to positive and gets added to 30 instead of subtracted from it.

hope this ! ^w^