Question: Two particles are fixed to an x axis: particle 1 of charge q1 = 2.91 x 10-8 C at x = 26.3 cm and particle 2 of charge q2 = -5.82q1 at x = 46.6 cm. At what coordinate on the x axis is the electric field produced by the particles equal to zero?

I am thinking: q1=2.91E-8C and q2=-1.694E-7C . I found the net electric field by using Coulomb's law, which is .0013 N/C. Now I need to find where the net E field is zero, and I thought that if I set E=0 I could find the r where E=0 but I can't seem to figure out how to do that. I can't just substitute E to find r ...I know it's not that hard but I'm experiencing a block...