Answer:
4(c+1.5)=21
Explanation:
There are 4 people, that paid both the cost of the game each one of them paid $1.50 extra dollars for the shoes. B and D would be incorrect as it somehow brings 6 into this, when everyone everyone is paying their $1.50 alone. C would be incorrect as you are implying that one an additional $1.50 was paid, however we know that 4 different people paid $1.50, not just one person