(1/4х+1/5d)•8dx-1/2d
5+4dx/20x•8dx-1/2d
(5+4dx)•(8dx-1)/40dx
40dx-5+32d.2.x.2.-4dx/40dx
36dx-5+32d.2.x.2./40dx
(1/4х+1/5d)•8dx-1/2d
5+4dx/20x•8dx-1/2d
(5+4dx)•(8dx-1)/40dx
40dx-5+32d.2.x.2.-4dx/40dx
36dx-5+32d.2.x.2./40dx