If 40% is 10 students then 80% would be 20 students and then 20% would be 5 students so the answer would be B
This would be a combination I believe not a permutation so the equation to use would be nCr= n!/(n-r)!r!
So 10C2=45
First turn into a improper fraction, then just simply flip it over. Here's an example: 2 1/3 = 7/3 So your reciprocal is 3/7
