Carla's order at Mcdonald's costs $7.50, but she has a coupon for $2.50. If she gets an additional 20% discount for being a senior citizen, how much does she pay for her order in dollars total?
Thoughts? Step-by-step reasoning:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
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First subtract the coupon amount from the price of the food: $7.50 - $2.50 = $5.00. Then subtract 20% from 100% to find out what percentage of the reduced price Carla pays: 100% - 20% = 80%. Now multiply the price after the coupon by the percentage Carla pays to find the final price: $5.00 * .8 = $4.00.
Thus, the answer is 4.