Concept:
Conditional probability:
\[
P(A|B) = \frac{\text{Favourable outcomes}}{\text{Total outcomes under condition}}
\]
Step 1: List odd numbers.
Odd numbers on a die: $\{1,3,5\}$
Step 2: Total possible outcomes (both odd).
\[
3 \times 3 = 9 \text{ outcomes}
\]
These are:
\[
(1,1),(1,3),(1,5),(3,1),(3,3),(3,5),(5,1),(5,3),(5,5)
\]
Step 3: Find favourable outcomes (sum = 8).
\[
(3,5), (5,3)
\]
Number of favourable outcomes = 2
Step 4: Compute probability.
\[
P = \frac{2}{9}
\]
Step 5: Final conclusion.
Thus, the required probability is:
\[
$\frac{2{9}$}
\]