 A solution of x of concentration 0.010 moles per decometer cube gives an absorbance of 0.50. What concentration is a solution of x, which gives an absorbance reading of 0.25? Assume that the same optical cell is used in both readings. So again, like I was saying, since you get a straight line plot, you can just do c1 over a1 equals c2 over a2. And then since we're solving for c2, we're going to isolate that variable. So c1 a2 over a1, like that. And then plug and show. So c1 0.0100. So of course, this is going to give you concentration values in the same concentration values that you started with. So a2 0.25 divided by 0.50, like that. So as you can see, there's that. So all you do is 0.01 times 0.25 divided by 0.5. And you really don't even have to do that. You've probably done that in your head is what I'm saying. Times 10 to the negative 3. And like I was saying, it's going to be in the same concentration. So mole per decometer, that would be the concentration of something that's absorbing at 0.25 if the same thing absorbed at 0.5 at this concentration. So it should be a lower concentration, which it is. Make sense? Any questions on that one? Thank you.