 Okay. Let's try this one. This one is actually just figuring out Planck's constant from this equation. E equals the constant times the frequency. So E here is the energy of the photon. Okay. So what is it asking? Another way of writing the relationship between energy and frequency is the energy of the photon equals some constant times the frequency of that photon. So what's the value of this constant? Again, like I said, you know Planck's constant, but that's what we're actually figuring out here. So what you need to do is rearrange this equation so we're solving for constant. Okay. So I'm just going to say constant equals k whole word. Or in this case, I guess I should just say it equals h. Okay. So when I rearrange this equation, I have each photon. So let's just rearrange this for, let's solve for h. So we got h equals divided by the frequency of that. And we got both of those numbers listed over here. So E of the photon is going to be 2.9 times 10 to the negative, and the V of the photon is, or the nu of the photon, I guess I should say, 4.46 times 10 to the 14 hertz. So if we divide this number into this other number, 2.95 times 10 to the negative 19 divided by 4.46 times 10 to the 14th, what do we get? Well, I got with 1, 2, 3 significant digits, 6.601 is 34. The thing you want to remember is that 1 hertz, 1 per second, like that. So if we cancel out there and there. And since this is second to the minus 1, it actually moves up to the numerator. So our final answer is going to be 6.61 times 10 to the negative 34th joules per second, or a time second. And hopefully you guys notice that that's really, really close to Planck's constant. And that's what you'll get when you take the energy of any photon and divide its frequency. You're always going to get Planck's constant. In fact, that's where Planck's constant came from.