Resposta :
Olá, adicida.
[tex]q= 900 - 3p \Rightarrow 3p=900-q \Rightarrow p=300-\frac q{3}\\\\ \varepsilon(p)=\frac{dp}{dq} \cdot \frac{q}{p}=-\frac13 \cdot \frac{900-3p}{p}=\frac{3p-900}{3p}=1-\frac{300}p[/tex]
[tex]\varepsilon(195)=1-\frac{300}{195}=-0,53846[/tex]
[tex]\varepsilon(215)=1-\frac{300}{215}=-0,39535[/tex]