Answer:
12 dimes, 8 nickels
Explanation:
1. Set up an equation. Since we know the relationship between how many dimes and how many nickels that he has, we can create values for them.
2. Say that the number of nickels is x, so the number of dimes would be 2x-4.
3. Since we know that all of the coins that he has is 20 coins, we can say that 2x-4+x=20.
4. Solve the equation. We get 3x=24, and x=8.
5. That means that the number of nickels is 8, and the number of dimes is 2(8)-4, which is 12.
Answer: Timmy has 12 dimes and 8 nickels.