Starting amount of lemonade: 5 gallons
Amount sold: 4 gallons
Amount left over: 5 - 4 = 1 gallon
Each person gets 1/8 of a gallon:
1 gallon / 8 = 0.125 gallons
So, each person gets 0.125 * 4 = 0.5 gallons.
Therefore, Tina and her friends were left with 1 gallon of lemonade, which they shared equally among the 4 of them, giving each person 1/2 of a gallon of lemonade.