When you select the matches click on the System option within the ticket in the portion beneath the matches and possible systems based on the number of matches shall appear and you can see the planned number of system combinations in the brackets.
The table of combination numbers:
Los resultados finales de los juegos ofrecidos se basan en los....
It is not possible to cancel tickets from the site.
All your tickets played can be seen within the My Account option, in the Ticket Review sub-option on the left.
Selected pairs can be seen in the Ticket option.