Answer
$\begin{split}
a_f & = \frac{f}{10 + f} \\
& \\
a_1 & = \frac{1}{10 + 1}\\
& = \frac{1}{11}\\
& \\
a_2 & = \frac{2}{10 + 2} \\
& = \frac{2}{12} \\
& = \frac{1}{6} \\
& \\
a_3 & = \frac{3}{10 + 3}\\
& = \frac{3}{13}\\
& \\
a_4 & = \frac{4}{10 + 4} \\
& = \frac{4}{14} \\
& = \frac{2}{7} \\
\end{split}$
Work Step by Step
Just substitute $a_k$ by the index, starting from 1, because the sequence is defined for $k\geq1$, substitute the values and calculate.
