－2009又六分之五-(+2008又三分之二)-(-4018又四分之三)+(-1又二分之一)
=-2009-5/6-2008-2/3+4018+3/4-1-1/2
=(-2009-2008+4018-1)-(5/6+2/3-3/4+1/2)
=-(10+8-9+6)/12
=-15/12
=-5/4
=-1又4分之1