1. The problem statement, all variables and given/known data http://i.imgur.com/ITrJq.png 2. Relevant equations F=kq1q2/r^2 (Coulomb's Law) 3. The attempt at a solution Whenever I try to get the answer, I keep coming up with 15.47cm. I found the Coulomb's law for the third particle in relation to the other two, then set those equations to each other. This let me cancel out k and the charge of the third particle, since it wasn't given in the first place. After that it was a simple algebraic solve to find the distance. But I feel like I'm missing something big, so I'm here for some assistance. Thanks so much ahead of time! You guys have saved me before. It's only worth one point, which is basically nothing, but I really need to know how to do this.