Problem $4(20$ pts$)$

$($a$)$ What is the dead load due to a $3-$inch thick cedar decking in terms of lb$/$ft$^2$ if the density of the cedar timber is $28$ lb$/$ft$^3?(10$ points$)$

$($b$)$ What is the dead load of that $3-$inch thick cedar decking in terms of lb$,$ if the density of cedar timber is $28$ lb$/$ft$^3$ and the deck has a width of $4$ ft and a length of $30$ ft $?(10$ points$).$