 Let's write the ion product expression for calcium phosphate, okay? So, everybody write out calcium phosphate if you don't know it, you better know it, okay? So, calcium phosphate, and since you all know your solubility rules, know that it's a quote-unquote insoluble or slightly soluble from what we know name. Okay, so calcium is 2 plus, right? And phosphate is 3 minus like that. So, calcium phosphate itself is going to be C8, 3, P04, 2. So that's the formula unit of calcium phosphate. And in order to write this ion product, so that's like Ksp, okay? So, we're going to have to remember the reaction equation, okay? So, the reaction equation for this would be 3CA2 plus AQS plus 2P043 minus AQS. Okay, so how do we do Ksp? Just like all the other Ks, it's going to be the products divided by the reactants. If the products and reactants are not liquids and solids, right? So, if we look, there's only solids for reactants, so it's only going to have the product concentrations involved, right? So, in this case, it's going to be C2 plus AQP04. So, again, if you don't know your polyatomics, it'll be very difficult to do these things. Any questions on this one?