Yellow House is an office building comprising 2,000 square metres Net Lettable Area (NLA). It was let one and a half years ago on Full Repairing and Insuring (FRI) terms at 305,000 per annum for a term of 20 years subject to five-yearly upward-only rent reviews. Blue House is a similar property nearby and it was recently let on an internal repairing lease (IRI) terms at a rent of 360,000 per annum for a term of 20 years subject to five-yearly upward-only rent reviews. The property was sold last week for 4,800,000.

(a) Making any assumptions you deem appropriate, value the freehold and leasehold interests in Yellow House.

(b) Briefly discuss the specific provision(s) of existing professional standards used to derive the above Net Lettable Area (NLA).