Answer:
Karen needed to put 5 gallons 3 quarts of gas into her boat on Monday and twice as much on Saturday. To convert 5 gallons 3 quarts to gallons, we can add the number of quarts to the number of gallons and convert the total to gallons. Therefore, 5 gallons 3 quarts is equal to 5 + 3/4 = 5.75 gallons. Twice as much is 2 x 5.75 = 11.5 gallons. Therefore, Karen needed a total of 5.75 + 11.5 = 17.25 gallons of gas for both days. Since she had an 18-gallon jug of gas available, she had enough gas for both days.