Answer
$i=-10cm$
Work Step by Step
Using the lens equation $$\frac{1}{f}=\frac{1}{p}+\frac{1}{i}$$ solve for $i$. $$\frac{1}{f}-\frac{1}{p}=\frac{1}{i}$$ $$\frac{p}{pf}-\frac{f}{pf}=\frac{1}{i}$$ $$\frac{p-f}{pf}=\frac{1}{i}$$ $$i=\frac{pf}{p-f}$$ Substituting known values of $p=+5.0cm$ and $f=+10cm$ yields an image distance of $$i=\frac{(10cm)(5.0cm)}{5.0cm-10cm}=-10cm$$
