document.write( "Question 675983: In a 30 mile race between Joe and Frank, Joe started an hour after frank and finished an hour before Frank. Joe's average speed was 1 mile per hour faster than Franks. Find Joe and Frank's average seed during the race. \n" ); document.write( "
Algebra.Com's Answer #420152 by josmiceli(19441)\"\" \"About 
You can put this solution on YOUR website!
Let \"+s+\" = Frank's speed in mi/hr
\n" ); document.write( "\"+s+%2B+1+\" = Joe's speed in mi/hr
\n" ); document.write( "\"+s%2A1+=+s+\" = Frank's head start in miles
\n" ); document.write( "\"+t+\" = Frank's time after his head start
\n" ); document.write( "\"+t+-+1+\" = Joe's time after Frank's head start
\n" ); document.write( "---------------
\n" ); document.write( "Frank's equation:
\n" ); document.write( "(1) \"+30+-+s++=+s%2At+\"
\n" ); document.write( "Joe's equation:
\n" ); document.write( "(2) \"+30+=+%28+s+%2B+1+%29%2A%28+t+-+1+%29+\"
\n" ); document.write( "--------------------------
\n" ); document.write( "(2) \"+30+=+s%2At+%2B+t+-+s+-+1+\"
\n" ); document.write( "(2) \"+30+=+t%2A%28+s+%2B+1+%29+-+%28+s+%2B+1+%29+\"
\n" ); document.write( "and
\n" ); document.write( "(1) \"+t+=+%28+30+-+s+%29+%2F+s+\"
\n" ); document.write( "Substitute this into (2)
\n" ); document.write( "(2) \"+30+=+%281%2Fs%29%2A%28+30+-+s+%29%2A%28+s+%2B+1+%29+-+%28+s+%2B+1+%29+\"
\n" ); document.write( "(2) \"+30+=+%281%2Fs%29%2A%28+30s+-+s%5E2+%2B+30+-+s+%29+-+%28+s+%2B+1+%29+\"
\n" ); document.write( "(2) \"+30+=+30+-+s+%2B+30%2Fs+-+1+-+s+-+1+\"
\n" ); document.write( "(2) \"+30%2Fs+=+2s+%2B+2+\"
\n" ); document.write( "(2) \"+30+=+2s%5E2+%2B+2s+\"
\n" ); document.write( "(2) \"+s%5E2+%2B+s+-+15+=+0+\"
\n" ); document.write( "Use quadratic formula
\n" ); document.write( "\"+s+=+%28-b+%2B-+sqrt%28+b%5E2+-+4%2Aa%2Ac+%29%29+%2F+%282%2Aa%29+\"
\n" ); document.write( "\"+a+=+1+\"
\n" ); document.write( "\"+b+=+1+\"
\n" ); document.write( "\"+c+=+-15+\"
\n" ); document.write( "\"+s+=+%28-1+%2B-+sqrt%28+1%5E2+-+4%2A1%2A%28-15%29+%29%29+%2F+%282%2A1%29+\"
\n" ); document.write( "\"+s+=+%28-1+%2B-+sqrt%28+1+%2B+60+%29%29+%2F+2+\"
\n" ); document.write( "\"+s+=+%28-1+%2B+sqrt%28+61+%29%29+%2F+2+\"
\n" ); document.write( "\"+s+=+%28+-1+%2B+7.8103+%29+%2F+2+\"
\n" ); document.write( "\"+s+=+6.8103%2F2+\"
\n" ); document.write( "\"+s+=+3.4051+\" mi/hr = Frank's speed
\n" ); document.write( "\"+s+%2B+1+=+4.4051+\" mi/hr = Joe's speed
\n" ); document.write( "My math could have got messed up- check it\r
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