$($Holding$-$period dollar gain and return$)$ Suppose you purchased $16$ shares of Diamond Company stock for $$24\mathrm{.}22$ per share on May $1,2016.$ On September $1$ of the same year, you sold $12$ shares of the stock for $$25\mathrm{.}68.$ Calculate the holding$-$period dollar gain for the shares you sold, assuming no dividend was distributed, and the holding$-$period rate of return.

a$.$ The holding$-$period dollar gain for the shares you sold is $$.$ Enter a negative number if it is a loss. $($Round to the nearest cent.$)$

b$.$ The holding$-$period rate of return is $\%.($Round to two decimal places.$)$