Answer: First, add 3.99 + 7.17. Then take the sum of those two numbers and multiply it by .05 to get 0.55. Since we are dealing money, round to the nearest hundredth to get .56. Add the sum of 3.99 and 7.17 (11.16) and .55 to get a total of 11.71. Therefore the total cost of their dinner, including tax, was $11.71.
Step-by-step explanation: