Answer
$12 \ candelas$
Work Step by Step
Step 1. Assume $I\ (candelas)$ is the illumination produced by a light source.
Step 2. Assume $d\ (m)$ is the distance from the source.
Step 3. From the given conditions, we have $I=k/d^2$ and $70=k/(5)^2$, thus $k=1750$
Step 4. For $d=12\ (m)$, we have $I=1750/(12)^2\approx12.153\approx12\ candelas$