Answer
$ R_{5}=44$, $ L_{5}=46$
Average=$\dfrac{44+46}{2}=45$
Work Step by Step
$\Delta x=\frac{b-a}{N}=\frac{1-0}{5}=\frac{1}{5}$
$ f(x_{j})=f(a+j\Delta x)=f(0+j\times\frac{1}{5})=f(\frac{j}{5})$
\begin{equation}
R_{N}=\Delta x\sum_{j=1}^{N}f(x_{j})
\end{equation}
$\implies $ \begin{equation}
R_{5}=\frac{1}{5}\sum_{j=1}^{5}f(\frac{j}{5})=\frac{1}{5}(f(\frac{1}{5})+f(\frac{2}{5})+f(\frac{3}{5})+f(\frac{4}{5})+f(\frac{5}{5}))=\frac{1}{5}(48+46+44+42+40)=44
\end{equation}
\begin{equation}
L_{N}=\Delta x\sum_{j=0}^{N-1}f(x_{j})
\end{equation}
$\implies $ \begin{equation}
L_{5}=\frac{1}{5}\sum_{j=0}^{4}f(x_{j})=\frac{1}{5}(f(\frac{0}{5})+f(\frac{1}{5})+f(\frac{2}{5})+f(\frac{3}{5})+f(\frac{4}{5}))=\frac{1}{5}(50+48+46+44+42)=46
\end{equation}
Average=$\dfrac{44+46}{2}=45$
