Final answer:
To calculate the cost of a goldfish with a 40% markup, add 40% of the original cost to the original cost.
Step-by-step explanation:
The subject of this question is Business and it is appropriate for High School level students.
To calculate the cost of a goldfish with a 40% markup, you first need to find 40% of the original cost. In this case, the markup is 40% of $7.50, which equals $3.00. You then add the markup to the original cost to get the total cost: $7.50 + $3.00 = $10.50.
Therefore, the cost of the goldfish after a 40% markup is $10.50.