It is equel to 30 pounds
Don't forget that we can only assume what material you are talking about. Since a quart is a volume measurement, and a pound is a weight measurement, you really need to specify the either the density (which is weight per volume) or the actual substance so we can look up the density. The answer by Aicha is accurate for water, but if you were talking about something else, like gasoline, the answer would be different - 40 quarts of gasoline weighs about 61.5 pounds.
0.5 quarts = 1 pound
1 quart = 1/0.5
40 quarts= 1/0.5 * 40
40 quarts = 80 pounds
1 quart = 1/0.5
40 quarts= 1/0.5 * 40
40 quarts = 80 pounds