Answer :
If you mean (x^3-8x)-(3x-2) then:
1) leave the (x^3-8x) part alone and use the distributive property on the -(3x-2).
2) your question now becomes x^3-8x-3x+2
3) combine the like terms: x^3-11x+2
1) leave the (x^3-8x) part alone and use the distributive property on the -(3x-2).
2) your question now becomes x^3-8x-3x+2
3) combine the like terms: x^3-11x+2