 Okay, so this question is a little more convoluted, I guess, you could say. Which solution is more concentrated, a 0.04% weight by weight solution, or a 50 ppm solution? So, you've got to remember the formula for both of these, weight, weight, and ppm. So, percent weight, weight equals mass. These are essentially the same equation here, except for the difference out here. These are the only differences in this equation. See that? Okay, so what you want to do actually in this equation is, this is your actual concentration units, is solute over solution. So, you can set this equal to something else. Okay, so you're just going to compare this in this number, okay? So, we'll say mass solute over mass is a solution. Since that's the concentration, we'll just set it equal to C, okay, for concentration. So, now we have a different equation. So, both of these are C now, right? Because this is mass solute over mass is solution, mass solute mass is solution. So, let's just go ahead and erase this and put C. Now, we've got ppm equals C times n, and percent weight weight equals C times 100%. Okay? So, now let's just, we've got values we could plug in for percent weight weight and ppm, right? So, for percent weight weight, that equals 0.04%. And for ppm, so if we just, we want to isolate C here, okay? So, we could say this is C1 and this is C2. Let's go ahead and isolate that. So, for C1, just divide both sides by 100%. Now, it equals percent weight weight over 100%. C2 is essentially the same. It's now ppm by 100%. So, now all you've got to do is plug in those values. Sorry, not 100%. It's 10 to the 6th. So, if you just plug in these values, 0.04% divided by 100%. Percent's cancel. 0.04 divided by 100 to the negative 4. That's C1 is 4 times 7 to the negative 4. So, if we plug in 50 ppm for this one and divide it by a million ppm. 50 divided by 10 to the 6th. And we get 5. So, then we compare these two numbers here. And we say which one's bigger, this one or this one? Well, this one's bigger. Okay? So, which solution is more concentrated? That one next. 0.04%. This is bigger. Numbering.