<p>Grubers Math WB pg. 154</p>

<h1>5</h1>

<p>A man can drive a certain distance in 5 hours. If he increased his speed by 10 miles per hour, he could travel the same distance in 4 1/6 hours. What is the distance he traveled.</p>

<p>I get that D = R x T, but I've been stuck on this for like 10 min.</p>

<p>and</p>

<p>Paul and Mary can do a job in 2 hours. When Paul works alone, he can do 5 jobs in 15 hours. How many hobs can Mary do in 12 hours, alone? </p>

<p>Sorry, I kind of suck at math!</p>

<ol>

<li><p>D=rate1<em>5=rate1</em>30/6 and D=rate2<em>25/6. Set the two equal. rate1</em>30/6=rate2<em>25/6 so rate1</em>30=rate2<em>25. Since rate2=rate1+10, you substitute to get rate1</em>30=(rate1+10)<em>25. So, rate1</em>30=rate1<em>25+250. Doing algebra, rate1</em>5=250, rate1=250/5=50 miles per hour. So, D=50*5=250 miles.</p></li>

<li><p>Paul can do 5 jobs in 15 hours, or 1 job in 3 hours, or 1/3 jobs per hour. In two hours, Paul can thus do 2<em>(1/3) jobs = 2/3 jobs. Thus, for Paul AND Mary to do one job in two hours, Mary has to do the remaining 1/3 jobs in that two hours, meaning she does (1/3)/2=1/6 jobs per hour. Thus, in 12 hours alone, Mary does (1/6)</em>12=2 jobs.</p></li>

</ol>