A point charge q1q1q_1 = 4.10 nCnC is placed at the origin, and a second point charge q2q2q_2 = -3.05 nCnC is placed on the xx-axis at x=+x=+ 20.5 cmcm. A third point charge q3q3q_3 = 1.90 nCnC is to be placed on the xx-axis between q1q1 and q2q2. (Take as zero the potential energy of the three charges when they are infinitely far apart.)

Where should q3q3 be placed between q1q1 and q2q2 to make the potential energy of the system equal to zero?