Different partners may quote different prices for the same flight. This is due to different partnership terms and conditions with airlines and applicable service fees. At the bottom right of the screen, you can see prices offered by other partners for the flight that you selected. The prices are based on how many tickets you want to buy, the ages of passengers, and the service class you selected.
To book one of the tickets you see, click Buy to the right of the appropriate option. The partner site will open in a new tab in your browser; you can proceed to book and pay for your ticket there.
After completing the booking process, check your ticket status.