proportional rate

A bacteria culture starts with 760 bacteria and grows at a rate proportional to its size. After 2 hours there will be 1520 bacteria. Express the population after t hours as a function of t.

mixing problem

a tank contains 1320 L of pure water. A solution that contains .01kg of sugar per liter enters a tank at the rate 3L/min. The solution is mixed and drains from the tank at the same rate. Find the amount of sugar after t minutes as a function of t.

help solving separable equation in mixing problem

A tank contains 1320L of pure water.A solution that contains .o1kg of sugar per liter enters a tank at the rate 3L/min The solution is mixed and drains from the tank at the same rate. Solve for function of t So far I have the equation: dy/dt = (.01)(3)-(y(t)/1320)*(3) but I guess I am not understanding how to solve this equation.

exact equation

The following differential equation is exact. Find a function F(x,y) whose level curves are solutions to the differential equation: ydy-xdx=0 "F(x,y) such that the solutions are F(x,y)=c for an arbitrary constant c".

explicit/implicit solutions to diff. equation

Find an explicit or implicit solutions to the differential equation: (x^2 + 4xy)dx + xdy = 0 "F(x,y) such that the solutions are F(x,y)=c for an arbitrary constant c".