The answers given in my book are $12, 10$ respectively.
I consider the function $(1 + Y^5 + Y^{10})(1 + Y^2 + Y^4 + Y^6 + Y^8 + Y^{10})(1 + Y + Y^2 + \ldots + Y^{10})$ where $Y$ stands for a $5$-cent unit.
I use synthetic multiplication to multiply through the polynomials.
Wasn't able to get the numbers perfectly aligned. So,
$1 1 1 1 1 1 1 1 1 1 1\\ 1 0 1 0 1 0 1 0 1 0 1 \\ – - - - - - \\ 1 1 1 1 1 1 1 1 1 1 1 \\ \quad 1 1 1 1 1 1 1 1 1 1 1 \\ \qquad 1 1 1 1 1 1 1 1 1 1 1 \\ \quad \quad \quad 1 1 1 1 1 1 1 1 1 1 1 \\ \quad \quad \quad \quad 1 1 1 1 1 1 1 1 1 1 1 \\ \quad \quad \quad \quad \quad 1 1 1 1 1 1 1 1 1 1 1 \\ – - - - - - - - - - - \\ 1 1 2 2 3 3 4 4 5 5 6 5 5 4 4 3 3 2 2 1$
and
$1 1 2 2 3 3 4 4 5 5 6 5 5 4 4 3 3 2 2 1 \\ 1 0 0 0 0 1 0 0 0 0 1 \\ – - - - - - \\ 1 1 2 2 3 3 4 4 5 5 6 5 5 4 4 3 3 2 2 1 \\ \quad \qquad 1 1 2 2 3 3 4 4 5 5 6 5 5 4 4 3 3 2 2 1 \\ \qquad \quad \quad \quad 1 1 2 2 3 3 4 4 5 5 6 5 5 4 4 3 3 2 2 1 \\ – - - - - - - - - - - \\ 1\ 1 \ 2 \ 2 \ 3 \ 4 \ 5 \ 6 \ 7 \ 8 \ 10 \ 10 \ 11 \ 11 \ 12 \ \color{red}{\fbox {12}} \ 12 \ 11 \ 11 \ 10 \ \color{blue}{\fbox 9} \ 8 \ 7 \ 6 \ 5 \ 3 \ 3 \ 2 \ 2 \ 1$
So my answers are $12, 9.$
Are my calculations correct? If they are not, what can I do to fix the whole thing? Thanks.
The answer---as Thomas Andrews points out---should be symmetric, and indeed it looks like you forgot a $1$ at the end of your first synthetic multiplication.