Let x = the number of quarters that Amy has. Since she has a total of 38 coins, the number of nickels is 38-x. Each quarter is worth $0.25 (25 cents) and each nickel is worth $0.05 (5 cents):
($0.25)*x + ($0.05)*(38-x) = $5.70
0.25x + 1.9 - 0.05x = 5.70
0.20x = 3.8
Solve for x.
