If you have twice as many nickles as dimes, you have to have an even number of nickles. You have one more quarter than # of nickles, so lets try 2 dimes , 2 x 2 would be 4 nickles, and 1 more than 4 would give you 5 quarters; to solve: 5 quarters = 1.25 + 2 dimes = .20, +4 nickles = 20 for a total of $1.65....first try!