X^4-3x³+4x
x^4-3x³+3x+x
(x^4+x)-(3x³-3x)
x(x³+1)-3x(x²-1)
x(x+1)(x²-x+1)-3x(x+1)(x-1)
x(x+1)(x²-x+1-3x+3)
x(x+1)(x²-4x+4)
x(x+1)(x-2)(x-2)
so x intercepts are (0,0), (-1,0) and (2,0)
the y intercept is (0,0)
6/12=X/18
Using the ratio of 18:12, you multiply 18/12 with 6, which equals 9.
Answer: NJ=9
A and d seem correct to me.
b and c are definitely wrong.
There are 
ways of picking 2 of the 10 available positions for a 0. 8 positions remain.
There are 
ways of picking 3 of the 8 available positions for a 1. 5 positions remain, but we're filling all of them with 2s, and there's 
way of doing that.
So we have
The last expression has a more compact form in terms of the so-called multinomial coefficient,
