【1】-2n-[3n-1]
=-2n-3n+1
=-5n+1
【2】-3[2s-5]+6s
=-6s+15+6s
=15
【3】3[-ab+2a]-[3a-b]
=-3ab+6a-3a+b
=-3ab+3a+b
【4】3[xy-2z]+[-xy+3z]
=3xy-6z-xy+3z
=2xy-3z
【1】-2n-[3n-1]
=-2n-3n+1
=-5n+1
【2】-3[2s-5]+6s
=-6s+15+6s
=15
【3】3[-ab+2a]-[3a-b]
=-3ab+6a-3a+b
=-3ab+3a+b
【4】3[xy-2z]+[-xy+3z]
=3xy-6z-xy+3z
=2xy-3z