Question Number 193323 by fit last updated on 10/Jun/23
Answered by MM42 last updated on 10/Jun/23
$$\left.\mathrm{9}\right)\:{n}\left({s}\right)=\mathrm{80}\:\&\:{n}\left({m}\right)=\mathrm{40}\:\&\:{n}\left({e}\right)=\mathrm{65} \\ $$$${n}\left({s}\right)={n}\left({m}\right)+{n}\left({e}\right)−{n}\left({m}\cap{e}\right) \\ $$$$\mathrm{80}=\mathrm{40}+\mathrm{65}−{n}\left({m}\cap{e}\right)\Rightarrow{n}\left({m}\cap{e}\right)=\mathrm{15} \\ $$$$\left.\mathrm{10}\right)\frac{\mathrm{15}!}{\mathrm{3}!\mathrm{2}!\mathrm{2}!\mathrm{2}!\mathrm{2}!\mathrm{2}!} \\ $$$$\left.\mathrm{11}\right)\mathrm{10}×\mathrm{9}×\mathrm{8}×\mathrm{7} \\ $$