Final answer:
To simplify the expression, combine like terms by adding or subtracting their coefficients. The simplified expression is -a - 8b - 5c.
Step-by-step explanation:
To simplify the expression, b - 4c + 3a - c - 9b - 4a, we need to combine like terms. Like terms are those that have the same variables and exponents. We can combine the terms by adding or subtracting their coefficients.
Starting with the coefficients of 'b', we have (-9b + b), which simplifies to -8b. Next, combining the coefficients of 'c', we have (-4c - c), which simplifies to -5c. Finally, for the coefficients of 'a', we have (3a - 4a), which simplifies to -a.
Therefore, the simplified expression is: -a - 8b - 5c.