The number of positive integer solutions for the equation x +y +z + t = 15 is  Choose the correct choice from the following answers:
A) 654
B) 584
C) 384
D) 364
E) 394

Rationale: the number of positive integer solutions for the equatio fx 1 + x 2 + ⋯ + xn = k ( k - 1 ) c ( n - 1 ) - where k is the number and n is number of variable in the equation . 15 - 1 c 4 - 1 = 14 c 3 = 364 answer : d
Answer: D