impairment

Hi,

i am doing impairment question in BPP rev kit and cannot undertsand pro rota

Question ask

cash generating unit comprises the following Assets:

$000

Building 700

Plant and equipment 200

Good Will 90

Current Assets 20

Total 1,010

one of the machine carried at $40,000, is damaged and will have to scrapped.The recoverable amount of the cash generating unit is at $750,000

What will be the carrying amount of the building when the impairment loss has been recognised.

i do understand the imapairment loss recognisedis $130,000 but dont understand how that pro rota into building and plant.

please help to pro rota that:

many thanks