Add punctuation: 21 The six companies
A: 2.1 The six companies

Add punctuation: The lovely living room has a minimalist style with exquisite decor adding a touch of freshness and elegance to the entire apartment
A: The lovely living room has a minimalist style with exquisite decor adding a touch of freshness and elegance to the entire apartment.

Add punctuation: Oil is a mixture of different carbon chains and to separate them from each other the oil must be heated
A:
Oil is a mixture of different carbon chains, and to separate them from each other, the oil must be heated.