The correct option that can be represented by the equation 3x = 24 is:
d. The cost of a pair of shoes is three times the cost of a shirt. If the cost of the shirt is $24, how much does a pair of shoes cost?
In this case, let x represent the cost of the shirt. Therefore, 3x represents the cost of the pair of shoes. If 3x = 24, then x = 8, which means the cost of the shirt is $8. Therefore, the cost of a pair of shoes is 3 times $8, which is $24.