Please can someone help me to understand this question? I have a hard time trying to solve it and I feel I can't even start the first question

Consider a PN junction in which the N-side is doped at 5 times the doping at the P-side. The intrinsic carrier concentration is ni=1011cm3. The built-in voltage (contact potential) was measured to be 0.65V for this PN junction. (a) What are the doping concentrations on each side of the PN-junction? (consider temperature to be room temperature, T=300K) (b) Calculate the depletion width for the above PN junction in equilibrium (unbiased) condition. The material is made of relative dielectric constant 11.7. (c) What is the length of the depletion region on the N-side and the P-side