Help me find the last answer which the red one, question d). The answer that I have key in was wrong, that is why it shows red instead of green.

Can you show me the step with an explaination, thank youuu.

The air in a 41 cubic metre kitchen is initially clean, but when Amanda burns her toast while making breakfast, smoke is mixed with the room's air at a rate of 0.03 mg per second. An air conditioning system exchanges the mixture of air and smoke with clean air at a rate of 8 cubic metres per minute. Assume that the pollutant is mixed uniformly throughout the room and that burnt toast is taken outside after 43 seconds. Let 5(t) be the amount of smoke in mg in the room at time (in seconds) after the toast first began to bumn. a. Find a differential equation obeyed by S(t). b. Find S(t) for 0