A tank contains $1400$ L of pure water. A solution that contains $0.06$ kg of sugar per liter enters tank at the rate $3$ L/min The solution is mixed and drains from the tank at the same rate.

(a) How much sugar is in the tank at the beginning.
$y(0) =$ (include units)

(b) Find the amount of sugar (in kg) after $t$ minutes.
$y(t) =$ (function of $t$)

(b) Find the amout of the sugar after $78$ minutes.
$y(78)=$ (include units)