Therefore, KSP is equal to the concentration of barium times the concentration of sulfate ion. Finally, since this guy is 1.0 times cents and negative ten, we say KSP is equal to 1.0 times ten to negative ten equals. Now, since this is X and this is X, you write X is here. Now, since barium there's 1 mol of barrium, we put a one in front of the X for barium. And since there's a 1 mol of sulfate, we put the 1 mol in front of the X. So we get one X times one X equals X squared.