Question 1187142
The expansion of {{{(y+1)^10}}} is
{{{(y+1)^10=y^10=10y^9+45y^8+120y^7+210y^6+"..."}}} where the coefficient of {{{y^7}}} is {{{10*9*8/(3*2)=120}}} .
With {{{x^3=y}}} it is
{{{(x^3+1)^10=x^30=10x^27+45x^24+120x^21+210x^18+"..."}}}
When that is multiplied times {{{(1-3x)}}} the term in {{{x^22}}} will be
{{{(-3x)(120x^21)=-360x^22}}}
The coefficient of {{{x^22}}} is {{{highlight(-360)}}} .