Find the number of 500-ml portions in 8 litres of soup.<br><br>
&bull; 8 litres = 8000 ml<br>
&bull; Number of 500-ml portions = 8000 ÷ 500 = 16<br>
&bull; Soya sauce needed = 16 × 25 ml = 400 ml<br>
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Final Answer: 400 ml