Use
$a=\frac{ a }{ 1 }$ to convert the expression into a fraction
$\frac{ 1 }{ 13 } \times \frac{ 5 }{ 1 }$
To multiply the fractions, multiply the numerators and denominators separately
$\frac{ 1 \times 5 }{ 13 \times 1 }$
Any expression multiplied by
$1$ remains the same
$\frac{ 5 }{ 13 \times 1 }$
Any expression multiplied by
$1$ remains the same
$\begin{align*} & \frac{ 5 }{ 13 } \\ & \overline{}\end{align*}$