 Okay, so let's just go ahead and attempt this problem. It says, for each formula unit of sodium sulfate decohydrate, and then it gives you the formula unit, and that's written up there, what percentage of the atoms are sodium atoms, okay? So let's just figure this out. So the first thing we need to do is count up the number of atoms we have all together, right? We've got, well, sodium, we'll write all the atoms down, how about that? Sodium, sulfur, oxygen, and hydrogen, right? That's all the atoms we've got, okay? So we've got two sodiums. If we look, only one sulfur, four oxygens here, but then we have ten water molecules, so that's ten more oxygens, right? So all together that's fourteen. And then hydrogen is our last element, and so we have none over here. So two times ten, that's going to be twenty, okay? So the next thing we've got to do is add all of those numbers up. So just get your calculator out, because you can have a calculator on everything in this class. Two plus one plus fourteen plus twenty, it's going to be thirty-seven, okay? So it asks what percentage of the atoms are sodium atoms? So in order to do percent, in this case percent atoms, or sodium atoms in this case, that's going to equal the number of sodium atoms over the total number of atoms times one hundred percent. So if you look, right, we've got the number of sodium atoms right here as two, and we've got the total number of atoms right here as thirty-seven, and if we multiply that by a hundred percent, remembering that percentage is our units there, okay? So all we've got to do is take two, divide it by thirty-seven, multiply that by one hundred, and I think it asks, tells you how many sig figs it is, with units two sig figs. So it's, in this case, it's going to be five point four, and that's two sig figs, percentage is your units. So, cool with that one? So again, we're just going to, we'll put these on the, online, and you can go and look at them and tell all your friends that are going to take this class next semester.