The number of ways in which 10 persons can go in two boats , so that there may be 5 on each boat, supposing that two particular persons will not go in the same boat, is :
ᴬ.¹/²⁽¹⁰ᶜ⁵⁾
ᴮ.¹/²⁽⁸ᶜ⁵⁾
ᶜ.²×⁸ᶜ⁴
ᴰ.⁸ᶜ⁴