Hi @NataliiaK ,
1. For 'How to compare distance between two trend lines?',
You can create a measure like so:
distance between two trend lines ( A - B ) =
MAX ( 'Table'[A] ) - MAX ( 'Table'[B] )
2. For ‘Is it possible to make visual with trends and two different x axis, e.g. X - Sum, X -% and Y - date? ’,
Power BI does not currently support it. You can submit your idea here.
Or you can use 'Power KPI' and can refer to this article. This visual can have two different y axis. You can import it from marketplace.
This is my sample file.
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.