Both Laura and Sean arrive at the same answer of 8/3 by using different methods.
Laura starts by multiplying 2/3 by 4 to find the total amount of 2/3 in 4 units.
Sean starts by finding the total amount of 2/3 in one group and then multiplying that amount by the number of groups, 4.
Both methods lead to the same answer, so it doesn't matter which method is used. The important thing is that the answer is correct.