Answer
at least 263
Work Step by Step
final dimensions of the walkway will be $3\frac{1}{3}$ft by $35$ft
$\frac{4}{9}p\times\frac{9}{4}\geq\frac{350}{3}$
$\frac{4}{9}p\times\frac{9}{4}\geq\frac{350}{3}\times\frac{9}{4}$
$p\geq262.5$
round up because you can't have half of a paver
at least $263$
