Final answer:
Tommy has 40 nickels and 30 dimes. This was determined by setting up two equations from the given information about the number of coins and their total value, and solving for the number of each type of coin.
Step-by-step explanation:
The student is trying to determine the number of nickels and dimes Tommy has with the total being 70 coins and the value being $4.40. To solve this, we set up two equations based on the given information. Let d be the number of dimes and n be the number of nickels. The first equation will be n + d = 70 since the total number of coins is 70. The second equation is based on the total value, which translates to 0.05n + 0.10d = 4.40. By multiplying the second equation by 100 to remove the decimals, we get 5n + 10d = 440. From the first equation, we can express d as d = 70 - n. Substituting this into the value equation gives 5n + 10(70 - n) = 440, simplifying to 5n + 700 - 10n = 440. Solving this gives n = 40 and thus d = 30. Hence, the correct answer is C. 40 nickels and 30 dimes.