①n-{n-2+[5m-3(n+2m)+6n]}+2n
=n-{n-2+[5m-3n-6m+6n]}+2n
=n-{n-2+[3n-m]}+2n
=n-{4n-2-m}+2n
=n-4n+2+m+2n
=2-n+m
②½x-2（x-1/3y²）+（-3/2x+1/3y²）
=½x-2x+2/3y²-3/2x+1/3y²
=½x-2x+2/3y²-3/2x+1/3y²
= - 3x+y²
③2（t²-t-1)-(t²-t-1)+3(t²-t-1)
=(t²-t-1)(2-1+3)
=4(t²-t-1)
④-5（2m-n)-6(2n-3m)
=-10m+5n-12n+18m
=8m-7n
⑤-3（ab-5b²+2a²）-3（7ab+1ba²-25b²)
= -3（ab-5b²+2a²-7ab-1ba²+25b²)
= -3（2a²-6ab-1ba²+20b²)
= -3（2a²-6ab-1ba²+20b²)