document.write( "Question 484810: Daddy Lanz and his daughter shin leave home at the same time in separate automobiles. Daddy Lanz drives to his office, a distance of 24 km, and shin drives to school, a distance of 28 km. They arrive at their destinations at the same time. What are their Average rates, if daddy lanz's average rate is 12km/hr less than shin's? \n" ); document.write( "
Algebra.Com's Answer #331645 by htmentor(1343)\"\" \"About 
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Daddy Lanz and his daughter shin leave home at the same time in separate automobiles. Daddy Lanz drives to his office, a distance of 24 km, and shin drives to school, a distance of 28 km. They arrive at their destinations at the same time. What are their Average rates, if daddy lanz's average rate is 12km/hr less than shin's?
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\n" ); document.write( "Let R = Shin's rate
\n" ); document.write( "Then Daddy's rate = R - 12
\n" ); document.write( "Since rate = distance/time, and they arrive at the same time, the two rate equations are:
\n" ); document.write( "R = 28/t
\n" ); document.write( "R - 12 = 24/t
\n" ); document.write( "where t = the travel time
\n" ); document.write( "Solve for t in the 1st equation:
\n" ); document.write( "t = 28/R
\n" ); document.write( "Substitute into the 2nd equation:
\n" ); document.write( "R - 12 = 24/(28/R)
\n" ); document.write( "R - 12 = 24R/28
\n" ); document.write( "(4/28)R = 12
\n" ); document.write( "This gives R = 84 km/hr
\n" ); document.write( "Therefore, Daddy's rate = 84 - 12 = 72 km/hr
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