Answer:
dy/dx=-2y-5/2x
Step-by-step explanation:
The volume of the tank is (70 cm)³ = 343,000 cm³.
Now,
1 mL = 1 cm³
1 L = 1000 mL
so we convert the given rate to

Then the time it will take to fill up the tank is

Step 1: plug in 5 and 2 for your X and Y
Step 2: multiply 8*X or in this case 8*5 and you will get 40
Step 3: multiply 3*Y or in this case 3*2 and you will get 6
Step 4: subtract 40-6 and you will get 34