Setting the equation equal to 1 and solving for k:
Quote:
6/k(2+1) = 1
k(2+1) = 6*1
k(3) = 6
k = 6/(3)
k = 2

Setting the equation equal to 9 and solving for k:
Quote:
6/k(2+1) = 9
k(2+1) = 6*9
k(3) = 54
k = 54/(3)
k = 18

k = 2 in the OP, ∴ the solution is 1.