Taxable benefits John

Hi,

I have a question on “Employment income”.

In BPP this is question 47 – John is employed y Zebra Plc and gets a laptop.

Provided computer personal use: 6 November 2018
Market value first provided 3500 GBP
Market value when provided to John 2000 GBP
Zebra gave the computer to John on 5 April 2020 with a market value of 1000 GBP.

WHat is the total taxable benefits?

The answer says 3300 GBP, or 2990 GBP if the first year of provision was taxed in full , 1720 GBP using the lower value for the gift and 1833 GBP is using the 2000 when the asset was provided.

I’m a bit confused on how did they get to these answers, any help is appreciated.