The town of Cleanville lies next to a lake, which the residents of the town use for fishing, boating, and other recreational activities. Last year, two firms, Filth Inc. and Sludge Inc., built factories on the other side of the lake and have been dumping trash into it. Although some of the trash will dissipate naturally, the amount of trash the two firms emit is too much for the lake to handle. Right now, each firm dumps 40 pounds of trash in the lake each year (total of 80 pounds). Environmental scientists in Cleanville estimate that the lake can handle only 30 pounds of trash per year. The table below reports the marginal costs to the two firms of reducing trash. Pounds reduced Filth Inc.'s marginal costs Sludge Inc's marginal costs
(in $1,000s) (in $1,000s)
5 2 7
10 4 10
15 6 13
20 8 16
25 10 12
30 35 19
22 25 14
40 16 28
The marginal cost numbers tell us how much it would cost to reduce the marginal five pounds of trash. Therefore, Filth Inc's marginal cost of reducing the first 5 pounds is $2,000 and the next 5 pounds $4,000. Therefore, the total cost to reduce 10 pounds is $6,000. Suppose the city council agrees with the scientists' estimates and orders each firm to reduce trash by 25 pounds.
The total cost to reduce this amount of trash is $.