DC Analysis of FET-based circuit

Hi
the following question i don't understand why they have used the saturation mode equation to find Id. Because when i checked that Vsd > Vsd(sat)
so it should be in non-saturation mode.

where Vsd = 0.15 and Vsd = 4.2 so Vsd < Vsd(sat)
where Vsd(sat) =Vsg + Vtp = 5-0.8 = 4.2V



P.S