The answer is C first draw line y=x that's simply line that increases from left to right and has slope of one and goes thru origin. you now see its reflected
Let be the amount of fertilizer in the tank at time . Then
This ODE is separable, and you can write
Integrating both sides gives
At , there is no fertilizer in the tank, so . This means
so that the amount of fertilizer in the tank is given by
This function is constantly increasing, so it never achieves its maximum, but there is a strict upper bound as . You have lbs of fertilizer in the tank, which makes sense. Given enough time, the tank will be completely saturated with the fertilizer solution, so 2 lb/gal*100 gal = 200 lbs.