dq/dt = 55 the rate production is increasing and q = 400
Now we differentiate with respect to time -- note d(q^2)/dt = 2q dq/dt
dR/dt = 110dq/dt -q/100 dq/dt
dR/dt = 110(55)-(400/100)(55)
dR/dt = 6050 - 220 = 5830dollars/day
Thank you so much Calculus26. I'm just uncertain about the last answer, a friend of mine told it can't be $5830. He said that I might wanna try plugging in the derivative, but I 'm not sure what I'm getting wrong here.