1/4+5（x-1/2009)=1/2
5（x-1/2009)=1/2-1/4
5（x-1/2009)=1/4
4*5（x-1/2009)=4*1/4
20(x-1/2009)=1
3+20(x-1/2009)
=3+1
=4