To resolve an object in an electron microscope, the wavelength of the electrons must be close to the diameter of the object. What kinetic energy must the electrons have in order to resolve a protein molecule that is 3.90 nm in diameter? Take the mass of an electron to be 9.11*10^-31 kg.

I have gotten stuck and I am lost on how to solve this problem:
My work:
DeBroglie wavelength is found by: λ = h/mv,
h= h = Planck's constant = 6.626 x 10^-34 J*s
λ = 3.90 nm(1 m)/(10^9 nm) = 3.9 x 10^-9 m
electron velocity = v = h/mλ = (6.626 x 10^-34 J*s)/(9.11× 10–31 kg)(3.9 x 10^-9 m)
v=?

Question

To resolve an object in an electron microscope, the wavelength of the electrons must be close to the diameter of the object. What kinetic energy must the electrons have in order to resolve a protein molecule that is 3.90 nm in diameter? Take the mass of an electron to be 9.11*10^-31 kg. 

I have gotten stuck and I am lost on how to solve this problem: 
My work: 
DeBroglie wavelength is found by: λ = h/mv, 
h= h = Planck's constant = 6.626 x 10^-34 J*s 
λ = 3.90 nm(1 m)/(10^9 nm) = 3.9 x 10^-9 m 
electron velocity = v = h/mλ = (6.626 x 10^-34 J*s)/(9.11× 10–31 kg)(3.9 x 10^-9 m) 
v=?