PRR

Hi I need help to understand how the exempt figure for the third time the house was left unoccupied was calculated (for 46 months).

Q.) On 30 June 2021 Chester sold a house for £308,000, realising a chargeable gain of £190,000.
The house had been purchased on 1 January 2004 and throughout the 210 months of
ownership had been occupied by Chester as follows:
Months
69 Occupied
30 Unoccupied – Required to work elsewhere in the UK by his employer
22 Unoccupied – Travelling overseas
46 Unoccupied – Required to work elsewhere in the UK by his employer
43 Occupied
–––
210
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Throughout the period 1 January 2004 to 30 June 2021 Chester did not have any other main
residence.
This is the only disposal in the tax year 2021/22.