Final answer:
The correct solution to the equation 7.5d = 2.5d, after dividing by 2.5 and subtracting 2.5d, is d = 0, which corresponds to answer choice a) d = 0.
Step-by-step explanation:
The student is asking how to find the solution for a variable d when given the equation 7.5d = 2.5d with two different operations being applied by two different individuals: Lin divides the equation by 2.5 and Elena subtracts 2.5d from both sides of the equation. First, we will tackle the division part. If Lin divides both sides by 2.5, the equation becomes 3d = 1d. Next, we consider Elena's operation. If Elena then subtracts 1d from both sides, we end up with 2d = 0. Upon dividing both sides by 2 to solve for d, we get d = 0. Therefore, the correct answer to the given problem is a) d = 0.