document.write( "Question 939447: Pa got in his '29 Ford and started driving west from Jackson at a constant speed of 30 miles per hour. An hour later Ma got in her '31 Buick and started driving west from Jackson at a constant speed. After driving 4 hours Ma had passed Pa and was 10 miles ahead of him. How fast was Ma going? \n" ); document.write( "

Algebra.Com's Answer #572444 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
Pa's head start was $\"+30%2A1+=+30+\"$ mi
\n" ); document.write( "Start a stop watch when Ma leaves
\n" ); document.write( "Let $\"+d+\"$ = the distance Ma travels
\n" ); document.write( "in $\"+4+\"$ hrs
\n" ); document.write( "Let $\"+r+\"$ = Ma's rate in mi/hr
\n" ); document.write( "--------------------
\n" ); document.write( "Pa's equation:
\n" ); document.write( "(1) $\"+d+-+30+-+10+=+30%2A4+\"$
\n" ); document.write( "Ma's equation:
\n" ); document.write( "(2) $\"+d+=+r%2A4+\"$
\n" ); document.write( "----------------
\n" ); document.write( "(1) $\"+d+-+40+=+120+\"$
\n" ); document.write( "(1) $\"+d+=+160+\"$
\n" ); document.write( "and
\n" ); document.write( "(2) $\"+160+=+r%2A4+\"$
\n" ); document.write( "(2) $\"+r+=+160%2F4+\"$
\n" ); document.write( "(2) $\"+r+=+40+\"$
\n" ); document.write( "Ma's rate is 40 mi/hr
\n" ); document.write( "--------------------
\n" ); document.write( "check:
\n" ); document.write( "From the time Pa leaves he covers
\n" ); document.write( " $\"+30%2A%28+1+%2B+4+%29+=+150+\"$ mi
\n" ); document.write( "This is $\"+10+\"$ mi less than Ma's
\n" ); document.write( "distance as it should be\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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