Answer: 363 J

Given a variable force $F = (10-2x +3x^2 ) N$, Work done $W = \large\int \limits_a^b$$ F dx \rightarrow W = \large\int \limits_0^3$$ 10-2x+3x^2 dx $

$\Rightarrow W = [10x - 2x^2 + 3x^3]_0^3 = 10 (3) - 2 (3^2) + 3 (3^3) = 300-18 + 81 =363J$