Solving for A:"Solving for A: Finding Salt Concentration in Tank After 10 mins

[cbarker1]

Hello,

I need some help with part a. The problem state:
"Suppose a brine containing .2 kg of salt per liter run into a tank initially filled with 500L of water and 5 kg of salt. The brine enters the tank at a rate 5 L/min. The mixture, kept uniform by stirring, is flowing out at the rate of 5L/min.

a) Find the concentration, in kg per Liter, of salt in the tank after 10 mins.

Work for part a

$\d{A}{t}=RI-RO$

$A'=.2 kg/L*5 L/min-5L/min*A(t)/100 kg/L$

 

[Ackbach]

Hmm. Well, your units currently do not work out. Don't forget the algebraic rules for units (I'm sure you're familiar with these, but I just include them here for reference):

1. Units multiply the numbers they modify.
2. You can only compare ($<, \le, =, \ge, >$) identical units.
3. You can only add or subtract identical units.
4. Units can cancel by division, or square by multiplying, or square root by taking the square root.
5. The units of a derivative $\frac{dy}{dx}$ and units of $y$ divided by units of $x$.
6. The units of an integral $\int y \, dx$ are units of $y$ times units of $x$.

So, what needs to change for your equation to be correct? Hint: Think about the units of $A$.