Erdős Problem #712 — Determine, for any $k>r>2$, the value of $\frac{\mathrm{ex}_r(n,K_k^r)}{\binom{n}{r}},$ where $\mathrm{ex}_r(n,K_k^r)$ is the largest number of $r$-edges which can placed on $n$ vertices so that the…

Determine, for any $k>r>2$, the value of $\frac{\mathrm{ex}_r(n,K_k^r)}{\binom{n}{r}},$ where $\mathrm{ex}_r(n,K_k^r)$ is the largest number of $r$-edges which can placed on $n$ vertices so that there exists no set of $k$ vertices which is covered by all $\binom{k}{r}$ possible $r$-edges.