if wastewater is filling barrels at the rate of 7 quarts per hour and there are 24 hours in a day we start with,
7 x 24 = 168
and if the recycling facility picks up 25 full barrels on each trip, and each barrel holds 48 quarts of wastewater,
25 x 48 = 1,200
so we know that they fill 168 quarts each day and the facility makes a trip each time they've filled 1,200
1,200 ÷ 168 = 7.14285714286
so, there are 7 days between each pickup ( they come once a week )