a$.$ At what rate $($pounds per minute$)$ does salt enter the tank at time t$?$

$l\frac{b}{m}in$

b$.$ What is the volume of brine in the tank at time $t?$

gal

c$.$ At what rate $($pounds per minute$)$ does salt leave the tank at time t$?$

$|$ lb$/$min

d$.$ Write down and solve the initial value problem describing the mixing process.

$\frac{dy}{dt}=,y(0)=40.$

What is the solution to the initial value problem?

$y=$

e$.$ Find the concentration of salt in the tank $16$min after the process starts.

$l\frac{b}{g}al$

$($Type an integer or decimal rounded to the nearest tenth as needed.$)$