1) AuB {2,3,8,11}
AuC {2,3,5,8,11}
BuC {2,3,5,8,11}
2) AnB{2,3,8}
AnC{...}
CnB{11}
85-(х+24)=42
х+24=85-42
х+24=43
х=43-24
х=19