Question

Add a comma to the first sentence to separate the subordinate clause from the main clause

Answer 1

When talking about recycling, people don't seem to consider the recycling of clothing.

The comma should be placed between the first use of recycling and people. The subordinate clause is "when talking about recycling". This is a clause because of the word "when". When makes the reader wonder when what? The main clause is "people don't seem to consider the recycling of clothing."

Answer 2

When talking about recycling, people don't seem to consider the recycling of clothing.

That should be where you put a comma, hope I helped.