Jose has been collecting quarters and nickels. He empties his wallet to find that he has 24 coins (only quarters and nickel s) worth $3.80. How many quarters and how many nickels does jose have?

If all 24 of Jose's coins were nickels, he would have 24*$0.05 = $1.20. Since he has $3.80 - 1.20 = 2.60 more than that, and since each quarter that replaces a nickel adds $0.20 to the total, Jose must have 2.60/0.20 = 13 quarters.

Jose has 13 quarters and 11 nickels.