y=(4x+1)/(5x-3)
y(5x+3)=4x+1
5yx+3y=4x+1
(5y-4)x=1-3y
x=(1-3y)/(5y-4)
x,y互换 y=(1-3x)/(5x-4) (X不等于4/5)即为所求反函数.