480700. The different combinations of students that could go on the trip with a total of 25 student, but only 18 may go, is 480700.
The key to solve this problem is using the combination formula 
. This mean the number of ways to choose a sample of r elements from a set of n distinct objects where order does not matter and replacements are not allowed.
The total of students is n and the only that 18 students may go is r:
I think it’s 21.06. If not then sorry
It should be g(-3π) = sec(-3π)
I hope that helped.
Sarah spent $1,083 because $57*38=$2,166 and $2,166/2=$1083
