先化简再求值X-｛Y-2X+〔3X-2（2X+Y）+5Y〕｝,并求当X-Y=2的值

X-(Y-2X+(3X-2(2X+Y)+5Y))
=X-(Y-2X+(3X-4X-2Y+5Y))
=X-(Y-2X+(-X+3Y))
=X-(Y+3Y-2X-X)
=X-4Y+3X
=4X-4Y
当X-Y=2
X-(Y-2X+(3X-2(2X+Y)+5Y))
=4(X-Y)
=4*2
=8