Question
Let N denote the number that turns up when a fair die is rolled. If the probability that the system of equations
$x + y + z = 1$
$2x + \mathrm{N}y + 2z = 2$
$3x + 3y + \mathrm{N}z = 3$
has unique solution is ${k \over 6}$, then the sum of value of k and all possible values of N is :