Set up a proportion and solve for the missing term.<br><br>
&bull; 5 : _ = 20 : 16 means \(\frac{5}{x} = \frac{20}{16}\)<br>
&bull; Simplify the known ratio: 20 : 16 = 5 : 4 (divide both by 4)<br>
&bull; So 5 : _ = 5 : 4, therefore the missing term is 4.<br><br>
Final Answer: 4