Capital Gains Taxes on Seller Agent’s portion

Using simple numbers, I bought a house for 200k, sold it for 300k, so I gained 100k. But out of that 100k profit, I paid 5k closing costs and 5k to the seller agent, so I’m left with 90k. Do I pay capital gains tax on the 100k or 90k? And what percentage will the tax be? Because I see that it ranges between 15-20%.