Thanks for your comment and sorry for my wrongly posted.
I have not reviewed it as well as I should. The posted was edited as your comment.

By the way I’m very glad that readers give me feedback.

At this point the risk is 0%. If the contract price falls below the stop, all position will be closed. Traders will gain 20 from the first position and 20 from the second position but lose 20 from the last position. This makes 20 for traders as profit.”

This is wrong. With stop at 120, you’d have +20 profit on first, 0 zero profit on 2nd, and -20 loss on third. Gross profit is 0, not +20.

Thanks for correcting this.