Daniel is in a choir where all of the members have a different height. When the members are numbered from 1 to n in order of increasing height, he is number n/3. When numbered in reverse order, he is member number n − 9. How many members are in the choir?

Answer 1

n/3 = n-10

why not n-9?

Answer 2

n/3 = n - (n-9)
n/3 = 9
n = 27

Answer 3

remember the n/3 is from the left
but (n-9) is from the right and to compare it to n/3 we have to subtract