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<p>It is always nice to remember that this is the SAT, and that there are always different approaches to the same problem. When it comes to this type of problems, anyone who can move forward WITHOUT having to start with the basic d=rt formula will come ahead. </p>
<p>In this case, there are three approaches. </p>
<ol>
<li><p>Make the hill 60 miles. That is total 240 m. Add the hours for each leg (2,3,1,2) and divide 240 by 8. A = 30.</p></li>
<li><p>Apply the formula twice. The 30 and 20 yields 24. The 60 and 30 yields 40. The formula 2.24.40 / 24+40 = 30. </p></li>
<li><p>Realize that the 20 and 60 averages to 30 (2.20.60 / 20+60 = 30) and that the other two 30 will not change the average.</p></li>
</ol>