Final answer:
To determine the original salary before a 5% raise which resulted in a salary of $42,583, the calculation is $42,583 divided by 1.05. The correct original salary is $40,555.
Step-by-step explanation:
An assistant receives a 5% raise, bringing the salary to $42,583. To find the original salary before the raise, we need to reverse calculate the 5% increase. Since 5% is the increase, 100% would represent the original salary. We can express this as:
Original Salary + (Original Salary * 0.05) = New Salary
1.05 * Original Salary = $42,583
Original Salary = $42,583 / 1.05
Original Salary = $40,555
Therefore, the answer is a) $40,555.