3XY+10Y+[5X-(2XY+2Y-3X)]
=3XY+10Y+[5X-2XY-2Y+3X]
=3XY+10Y+（8X-2XY-2Y）
=3XY+10Y+8X-2XY-2Y
=3XY-2XY+10Y-2Y+8X
=XY+8Y+8X
=XY+8（Y+X）
∵XY=1,X+Y=3
∴原式=XY+8×（Y+X）=1＋8×3=25