[tex](n-10)(4n-10) -3\\\\=4n^2 -10n-40n+100-3\\\\=4n^2-50n+97\\\\=4n^2 -50n+96 +1\\\\=2(2n^2-25n+48)+1\\\\2(2n^2 -25n+48)~ \text{is even, so}~ 2(2n^2 -25n+48) +1~ \text{is odd.}[/tex]
[tex]\text{Hence,}~ (n - 10)(4n - 10) - 3 ~ \text{is always an odd number for}~ n\in \mathbb{W}.[/tex]