Answer:
$54,000 cost basis in ABC; $6,000 cost basis in DEF
Explanation:
The original cost basis is the price that was paid for the shares. This means that 1,000 shares at $60 each gives a cost basis of $60,000.
Now if the subsidiary DEF is worth 10% of ABC which has a cost basis of $60,000, then the share of DEF that customers will have will be 10% of $60,000.
(10÷100) x $60,000 = 0.1 x $60,000
= $6,000.
Now, if DEF is worth $6,000 (i.e 10%) of ABC, then ABC's worth will now be $60,000 - $6,000 = $54,000.
The original cost basis is that price that was paid for the shared initially. This means that it has no effect on the increase in value of the shares.
Cheers.