#### Answer

$33\text{ ft}$

#### Work Step by Step

Each duct is $3\frac{2}{3}$ ft long.
To find the total length of 9 pieces, multiply 9 and the length of each duct to obtain:
$=9 \times 3\frac{2}{3}
\\=9 \times \frac{3(3)+2}{3}
\\=9 \times \frac{11}{3}
\\=\frac{9(11)}{3}
\\=\frac{99}{3}
\\=33\text{ ft}$