Amanda has 21 coins in her piggy bank made up of nickels, dimes, and quarters. There are twice as many quarters as nickels and the total value of all the coins is $3.60. Let n = the number of nickels, d = the number of dimes, and q = the number of quarters. The system shown below represents this situation. q=2n n+d+q=21 0.05n+0.10d+0.25q=3.6 Amanda plans to set up an augmented matrix to solve the system. If she solves it correctly, how many quarters should be in her piggy bank?