So remember that dividing by a number is the same as multiplying by its reciprocal. So flip 2 to its reciprocal, change the division sign to multiplication, and solve as such:
[tex] \frac{8}{13}\times\frac{1}{2}=\frac{8}{26}\\\\\frac{8}{26}\div \frac{2}{2}=\frac{4}{13} [/tex]
Your final answer is 4/13.