Answer:
10 - A(t)/(1000 + t)
Step-by-step explanation:
salt enters the tank at the rate of 9 liters per minute, and is pumped out at 10 liters per minute.
V(0) = 1000 liters
V(t) = 1000 + t.
Let A(t) be the amount of salt in gram at time t
The concentration of salt entering the tank is 120 grams/liters.
grams/liters is the concentration of the salt that is being pumped out of the tank at time t
= 1 * 10 - A(t)/(1000 + t)
= 10 - A(t)/(1000 + t)