N(12-n)-5=4n-n(10+(n-3))

n(12-n)-5=4n-n(10+(n-3))

Решение: n(12-n)-5=4n-n(10+(n-3)) \ 12n - n^2 - 5 = 4n - 10n - n^2 + 3n \ 12n - n^2 - 5 = 4n - 10n - n^2 + 3n \ 12n - n^2 - 5 = -6n - n^2 \ 18n = 5 \ n = 5/18