From a class of 25 students, 10 are to be chosen for an excursion party. There are 3 students who decide that either all of them will join or none of them will join. In how many ways can the excursion party be chosen?

Explanation

If the students will join the party, then the combination will be,

`C_1`
=
`22_(C_7)`

=`170544`

If the students will not join the party, then the combination will be,

`C_2`=` 22_(C_10)`

​=`646646`

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