68. A solvent manufacturing company is producing toluene, and stocking it in two different vars with
10,000 gallons of capacity each. Vat A currently con-
cains 450 gallons of toluene, and its contents are
increasing at a rate of 40 gallons per minute. Vat B
currently contains 1,250 gallons of toluene, and its
contents are increasing at a rate of 15 gallons per min-
ute. In how many minutes will the two vats contain
equal amounts of toluene?