IF a Positive Quantity be multiplied by a Negative one, or contrariwise, the Product will be a Negative Quantity.
If a−b is to be multiplied by c; it is certain, that a multiplied by c, makes ac a Positive Quantity, by Consect. 1. Definit. 28. Moreover b by the same c (a Negative by a Positive) will make −bc; and so the whole Product of a−b by +c, will be ac−bc.