х=24000:80
х=300
24000:(300-12)=80
80=80
24 000:(x-12) = 80
24 000:(x-12):80 = 80:80
300:(x-12) = 1
300:(x-12)×300 = 1×300
x-12 = 300
x-12+12 = 300+12
x = 312
24 000:(312-12) = 80
ответ: х = 312
Удачи)))
