n0nsensical

So you need to find the electric field at the point (3.00,4.00). Use superposition to find the net field: add the fields that result from each charge at that point, which you find with Coulomb's Law.
e.g., to find the electric field created by particle 1:
Use Coulomb's Law E = 1/(4*π*ε_0)*(q / r^2) for the x- and y-components, which gives you a vector, (1/(4*π*ε_0)*(5.00 μC / (3.00 cm)^2), -1/(4*π*ε_0)*(5.00 μC / (4.00 cm)^2))

Do the same thing for particle 2 and add the vectors to get your answer. (Do a sanity check on all signs, they can be tricky)