Let the total number of customers be \(8u\) (lunch \(3u\), dinner \(5u\)).<br><br>
&bull; Lunch customers who order dessert = \(\frac{1}{1+2} \times 3u = \frac{1}{3} \times 3u = u\).<br>
&bull; Dinner customers who order dessert = \(\frac{3}{3+2} \times 5u = \frac{3}{5} \times 5u = 3u\).<br>
&bull; Total dessert orders = \(u + 3u = 4u\).<br>
&bull; Percentage = \(\frac{4u}{8u} \times 100\% = 50\%\).<br><br>
Final Answer: 50%