3[-(x+y)+2xy²-z]-2[(x+y)-xy²+z]-5[-3(x+y)-z]
=3(-x-y+2xy²-z)-2(x+y-xy²+z)-5(-3x-3y-z)
=-3x-3y+6xy²-3z-2x-2y+2xy²-2z+15x+15y+5z
=10x+10y+8xy²
=10(x+y)+8xy²
=10×(-10)+8×(-81)
=-100-648
=-748