A fish tank initially contains 15 liters of pure water. Brine of constant, but unknown, concentration of salt is flowing in at 4 liters per minute. The solution is mixed well and drained at 4 liters per minute. Let x be the amount of salt, in grams, in the fish tank after t minutes have elapsed.
a. Find a formula for the rate of change in the amount of salt, dx/dt, in terms of the amount of salt in the solution x and the unknown concentration of incoming brine c.
dx/dt =

Finally, the arena decides to offer advertising space on the jerseys of the arena’s own amateur volley ball team. the arena wants the probability of being shortlisted to be 0.14. what is this as a percentage and a fraction? what is the probability of not being shortlisted? give your answer as a decimal. those shortlisted are entered into a final game of chance. there are six balls in a bag (2 blue balls, 2 green balls and 2 golden balls). to win, a company needs to take out two golden balls. the first ball is not replaced. what is the probability of any company winning advertising space on their volley ball team jerseys?

Alex's monthly take home pay is $2,500. what is the maximum bad debt payment he can maintain without being in credit overload?

Can you me with this question? i'll reward *30 points i just need with this one question so that i could solve the others. * edit: i originally set up the question to reward 30 points, but for some reason i can only reward 15. if you don't get 30, then i'm sorry. i'm still kind of new to this site