PPE

Sir,

I am not able to understand the calculation done in the following example question

Example
Entities A and B are identical in all respects, except for their accounting policy for property, plant and equipment.
Both entities purchased an asset four years ago for $200,000. This was deemed to have a useful economic life of 10 years. Its fair value at the start of the current reporting period was $350,000.
Entity A uses the cost model. The current year depreciation charge on the asset is $20,000 ($200,000/10). The carrying amount of the asset in the statement of financial position at the year end is $120,000 (6/10 × $200,000).
Entity B uses the revaluation model. The asset was revalued at the start of the year by $210,000 ($350,000 – (7/10 × $200,000)). The depreciation charge on the asset in the current year is $50,000 ($350,000/7). The asset has a carrying amount in the statement of financial position of $300,000 ($350,000 – $50,000).

My question is
Why carrying amount of entity B takes 7 yrs and not 6 yrs with regards to
$350,000 – (7/10 × $200,000)) this calculation?

Thank you in advance