Final answer:
To simplify the expression (8x-3Y) - (9X + 8Y), distribute the negative sign to the second set of parentheses, combine like terms, and the simplified expression is -x - 11y.
Step-by-step explanation:
To simplify the expression (8x-3Y) - (9X + 8Y), we need to subtract each term in the second parentheses from the corresponding term in the first parentheses. We do this by distributing the negative sign to each term inside the second parentheses, which effectively changes the sign of each term:
8x - 3y - 9x - 8y
Next, we combine like terms, which in this case are the terms with x and the terms with y:
(8x - 9x) + (-3y - 8y) = -1x - 11y
The simplified version of the expression is -x - 11y.