Answer:
(Money they have) - (5.49 x 3) = dessert money
Step-by-step explanation:
It's impossible with the given information!
But, if you have the total money the girls have, then you can use the equation:
(Money they have) - (5.49 x 3) = dessert money
Subtract cost of 3 grilled cheese from total money they have to get the answer.