Definite Integration

Let \(T>0\) be a fixed number. \(f: R \rightarrow R\) is a continuous function such that \(f(x+T)=f(x), x \in R\)
If \(I=\int_\limits0^T f(x) d x\), then \(\int_\limits0^{5 T} f(2 x) d x=\)