2009÷(2009+2009/2010)+1/2011 =2009÷[2009*(1+1/2010)]+1/2011 =1÷(1+1/2010)+1/2011 =1÷2011/2010+1/2011 =1*2010/2011+1/2011 =2010/2011+1/2011 =1
