If the polynomial MX ^ 3 + 3nxy ^ 2-2x ^ 3 + XY ^ 2 + y contains no cubic term, then 2m + 3N =?

If the polynomial MX ^ 3 + 3nxy ^ 2-2x ^ 3 + XY ^ 2 + y contains no cubic term, then 2m + 3N =?

A:
Because there is no cubic term, the x ^ 3 coefficient is 0, and the XY ^ 2 coefficient is 0
m-2=0;3n+1=0
The solution is m = 2, n = - 1 / 3
So 2m + 3N = 2 * 2-3 * 1 / 3 = 4-1 = 3
2m+3n=3