12-4=8 дней
8*(1/12+(8-4 1/3)*х)=1
8/12+3 2/3*х=1
х*11/3=1-2/3
х*11/3=1/3
х=(1/3)/(11/3)=1/11
1/(1/11)=11 дней
12-4=8 дней
8*(1/12+(8-4 1/3)*х)=1
8/12+3 2/3*х=1
х*11/3=1-2/3
х*11/3=1/3
х=(1/3)/(11/3)=1/11
1/(1/11)=11 дней