Answer:
8.9
Step-by-step explanation:
1. DE:BC=AD:AB
2. AD=AB+BD, but according to the conditions AB=5, then
AD=5+BD.
3. after the substitution DE=16; BC=9; AB=5 and AD=5+BD into the formula:
16:9=(5+BD):5;
[tex]\frac{16}{9} =\frac{BD+5}{5};[/tex]
BD=80/9 - 5≈3.9.
4. if AD=AB+BD, then AD=5+3,9=8,9
