An electric charge q creates a field of 4500 N/C at a point d away from the charge. The potential at that point is +1800V. Determine q and d.

Do you have to use the formula E=kQ/r^2 or something else? I'm lost on how to solve it

V=kQ/d

then you can solve for Q/d=V/k

but E= kq/d^2
so we have two equations, two unknowns. Child's play.

Repost if you get stuck.