when (1 + ax + bx^2 + cx^3)^10 is expanded in ascending powers of x, the coefficients of x, x^2 , x^3 are 20, 200, 1000 respectively. Find the values of a, b , c and the coefficient of x^4.

Racked my brain and the internet looking for answers. Its for college algebra :S! any and all help appreciated thanks.