Answer :
You get 2 jugs of the 5 gallons and then take out 3 gallons using the 3 gallon jug. You end up getting 10-3=7 gallons.
Use a 5 gallon jug and then the 3 gallon jug. The 2 gallon jug should have marks on it where 1,2 and 3 gallons should be so instead of filling it to 3 fill it to 2