The first step is to distribute the negative sign to the expression (x3+4x4+2x2-10x) and after distributing the negative sign, the expression will become (-x3-4x4-2x2+10x). Then combine this with the first given expression (3x5+3x2−4x3+x−6) and this will become 3x5+3x2−4x3+x−6-x3-4x4-2x2+10x. then you can simplify it into 3x5-4x4+5x3+x2+11x-6.