Binomials

$(1+ax)^n=1+nax+\frac{n(n-1)}{2!}a^2x^2+\frac{n(n-1)(n-2)}{3!}a^3x^3+...$

Let  $na=10$

and    $\frac{n(n-1)}{2!}a^2=150$

and solve for a and n, then find c from $c=\frac{n(n-1)(n-2)}{3!}a^3$