Agallon of unleaded gasoline weighs about 6 pounds. about how many ounces does 1 quart of unleaded gasoline weigh?

To change units without changing the value, we use the Multiplicative Identity (that is, 1).

In this problem, we need:
(1 gallon)=(6 pounds) or 1 = (
(1 quart)=(1/4 gallon) or (4 quarts)=(1 gallon) or 1 = (
(16 ounces)=(1 pound) or 1 =
We have:
1 quart
(1 quart)*1
(1 quart)*((1 gallon)/(4 quarts))
(1 quart)*((1 gallon)/(4 quarts))*((6 pounds)/(1 gallon))*((16 ounces)/(1 pound))
(1)*(1/4)*(6/1)*(16/1) ounces [note: gallons, quarts, pounds all cancel out]
24 ounces

Checking: If a gallon weighs 6 pounds, a quart weighs 1.5 pounds [that is, 6/4].
That's 24 [that is, 1.5*16] ounces. Yes.