`(x(x+1/2)-1/5x -1/10)/3 . (x(x-1/2)-1/3x+1/6)/5`

`(x(x+1/2)-1/5 x-1/10)/3 . (x(x-1/2) - 1/3x + 1/6)/5`
`=(x^2 + 1/2 x - 1/5 x - 1/10)/3 . (x^2 - 1/2 x - 1/3 x + 1/6)/5`
`=(x^2 + 3/10 x  -1/10)/3 . (x^2-5/6 x + 1/6)/5`
`=((x^2 + 3/10 x - 1/10)(x^2 - 5/6x + 1/6))/15`
`=(x^2(x^2 - 5/6 x + 1/6) + 3/10 x (x^2 -5/6 x + 1/6) - 1/10(x^2-5/6 x + 1/6))/15`
`=(x^4 - 5/6 x^3 + 1/6 x^2 + 3/10 x^3 - 1/4 x^2 + 1/20 x - 1/10 x^2+1/12 x - 1/60)/15`
`=(x^4 - 8/15 x^3 - 11/60 x^2 + 2/15 x - 1/60)/15`