Answer
(a). $P=\frac{c}{W^k},$
(b). $P=1866.066$ or $P=1866$ people
Work Step by Step
$\log P=\log c - k\log W$
(a). $\log P=\log c - k\log W,$
$\log P=\log c - \log W^k$
$\log P=\log {\frac{c}{ W^k}},$
$P=\frac{c}{W^k}$,
(b). $k=2.1, c=8000, W=2,$
$P=\frac{8000}{2^{2.1}}=1866.066$ or $P=1866$ people