ex 1,va rogg,fdau coroana

5²-[51:(2²•5-15:5)+42:7+3]=
25-[51:(4•5-15:5)+42:7+3]=
25-[51:(20-3)+42:7+3]=
25-(51:17+42:7+3)=
25-(3+6+3)=
25-(9+3)=
25-12=
13