document.write( "Question 650320: Mike drove to a friends house at a rate of 40 miles mph. The return trip he traveled at a rate of 45 mph. Total driving time was 4 hours. What is the distance Mike traveled? \n" ); document.write( "

Algebra.Com's Answer #407281 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
Let $\"+d+\"$ = distance to friend's house in miles
\n" ); document.write( "Let $\"+t+\"$ = time in hrs to drive to friend's house
\n" ); document.write( "given:
\n" ); document.write( "To friend's house:
\n" ); document.write( "(1) $\"+d+=+40t+\"$
\n" ); document.write( "Return trip:
\n" ); document.write( "(2) $\"+d+=+45%2A%28+4-t+%29+\"$
\n" ); document.write( "-------------------
\n" ); document.write( "Substitute (1) into (20
\n" ); document.write( "(2) $\"+40t+=+45%2A%28+4-t+%29+\"$
\n" ); document.write( "(2) $\"+40t+=+180+-+45t+%29+\"$
\n" ); document.write( "(2) $\"+85t+=+180+\"$
\n" ); document.write( "(2) $\"+t+=+36%2F17+\"$
\n" ); document.write( "(2) $\"+t+=+2.1176+\"$
\n" ); document.write( "Plug this result back into (1) or (2)
\n" ); document.write( "(1) $\"+d+=+40t+\"$
\n" ); document.write( "(1) $\"+d+=+40%2A%28+36%2F17+%29+\"$
\n" ); document.write( "(1) $\"+d+=+84.706+\"$
\n" ); document.write( "and $\"+2d+=+169.412+\"$
\n" ); document.write( "Mike traveled 169.412 mi
\n" ); document.write( "check:
\n" ); document.write( "(2) $\"+84.706+=+45%2A%28+4-t+%29+\"$
\n" ); document.write( "(2) $\"+84.706+=+180+-+45t+\"$
\n" ); document.write( "(2) $\"+45t+=+180+-+84.706+\"$
\n" ); document.write( "(2) $\"+45t+=+95.294+\"$
\n" ); document.write( "(2) $\"+t+=+2.1176+\"$
\n" ); document.write( "OK \r
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