#### Answer

$P(-5)=-9,323$

#### Work Step by Step

Substituting $x$ with $ -5 $ in the given polynomial equation, $P(x)=3x^5-9x+7,$ then, \begin{array}{l}\require{cancel} P(-5)=3(-5)^5-9(-5)+7 \\\\ P(-5)=3(-3,125)-9(-5)+7
\\\\
P(-5)=-9375+45+7 \\\\
P(-5)=-9,323
.\end{array}