Answer: 5(√3-1) unit.
Step-by-step explanation:
Since, By the below diagram,
For triangle BDC,
We can write,

⇒ 
⇒ 
⇒ 
⇒ 
Now, In triangle ADC,

⇒ 
⇒ 
⇒ 
⇒ 
⇒ 
8= 2 liters of punch
16= 4 liters of punch
20= 5 liters of punch
28= 7 liters of punch
The answer is 357/88 but if u simplify it the answer is 4 5/88