A large vat is initially filled with a saltwater solution. A solution with a higher concentration of salt flows into the vat, and solution flows out of the vat at the same rate. The number of pounds of salt in the vat at time  t minutes is modeled by the function  A that satisfies the differential equation  ⅆAⅆt=6−0.02A. At time  t=10 minutes, the vat contains 50 pounds of salt.