document.write( "Question 949251: an athlete runs at 9 mph and then at 12 mph, covering 10 miles in one hour. how long does the athlete run at each speed? using the substitution method. \n" ); document.write( "

Algebra.Com's Answer #579545 by Fombitz(32388) $\"\"$ $\"About$

You can put this solution on YOUR website!
Rate x Time= Distance
\n" ); document.write( " $\"9%2At%5B1%5D%2B12%2At%5B2%5D=10\"$
\n" ); document.write( " $\"t%5B1%5D%2Bt%5B2%5D=1\"$
\n" ); document.write( "So then,
\n" ); document.write( " $\"t%5B1%5D=1-t%5B2%5D\"$
\n" ); document.write( "Substituting into the first equation,
\n" ); document.write( " $\"9%281-t%5B2%5D%29%2B12t%5B2%5D=10\"$
\n" ); document.write( " $\"9-9t%5B2%5D%2B12t%5B2%5D=10\"$
\n" ); document.write( " $\"3t%5B2%5D=1\"$
\n" ); document.write( " $\"t%5B2%5D=1%2F3\"$
\n" ); document.write( "So then,
\n" ); document.write( " $\"t%5B1%5D%2B1%2F3=1\"$
\n" ); document.write( " $\"t%5B1%5D=2%2F3\"$
\n" ); document.write( "2/3 hr(40 min) at 9 mph and 1/3 hr(20 min) at 12 mph
\n" ); document.write( " \n" ); document.write( "

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