A vendor has six jugs of punch with capacities of 13, 15, 16, 21, 21, and 22 gallons. One jug, which he keeps for himself, is full of blue punch. The other five jugs are full of red punch. Without opening any of the jugs, he sells 1/3 of the red punch to Randy and the remaining 2/3 of the red punch to Lisa. How many gallons of the blue punch did he keep for himself?
The vendor sells the jugs containing 13 , 15, 16, 21 and 22 gallons
This totals 87 gallons
1/3 of this = 29 gallons which means that he sells the jugs containing 13 and 16 gallons to Randy
The remaining 2/3 = 58 gallons which means that he sells the jugs containing 15, 21 and 22 gallons to Lisa
He keeps the remaining jug which contains 21 gallons of blue punch