Final answer:
The expression 0.75z - 6.75 is already in its simplest form, so the correct answer is 1) 0.75z - 6.75.
Step-by-step explanation:
The question asks for the simplified form of the algebraic expression 0.75z - 6.75. When simplifying an expression, you generally want to combine like terms or simplify the coefficients and constants, but in this case, the expression is already in its most simplified form. None of the provided answer choices further simplify the original expression. Therefore, the correct answer is 1) 0.75z - 6.75, as it is already simplified.