Average speed = Total distance &divide; Total time.<br><br>
&bull; Total distance = 3 &times; 30 = 90 km.<br>
&bull; Time for each segment:<br>
&bull; Segment 1: 30 &divide; 30 = 1 h<br>
&bull; Segment 2: 30 &divide; 45 = \(\frac{2}{3}\) h<br>
&bull; Segment 3: 30 &divide; 90 = \(\frac{1}{3}\) h<br>
&bull; Total time = 1 + \(\frac{2}{3}\) + \(\frac{1}{3}\) = 2 h.<br>
&bull; Average speed = 90 &divide; 2 = 45 km/h.<br>
<br>
Final Answer: 45 km/h