Elisa and her two friends went out to dinner. Each of them ordered a meal worth $10. Afterwards, they each had a scoop of the same kind of ice cream. If the $45 Elisa had was enough to pay for everything, what was the cost of a scoop of ice cream? Let's think first. Chain of thought:
The three friends had meals worth 10 * 3 = 30 dollars. If they paid for the meals only, they would have remained with 45 - 30 = 15 dollars. Dividing the remaining amount by the number of ice cream scoops gives 15 / 3 = 5 dollars. Each scoop of ice cream cost 5 dollars.
Therefore, the answer is 5.