document.write( "Question 696364: A father and his son can do a job in 20 days. The father can do four times as much work as his son in a given amount of time. In how many days can the father do the job alone? \n" ); document.write( "

Algebra.Com's Answer #428983 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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A father and his son can do a job in 20 days.
\n" ); document.write( " The father can do four times as much work as his son in a given amount of time.
\n" ); document.write( " In how many days can the father do the job alone?
\n" ); document.write( ":
\n" ); document.write( "let d = time required by Dad working alone
\n" ); document.write( "then
\n" ); document.write( "4d = time required by sonny
\n" ); document.write( ":
\n" ); document.write( "let the completed job = 1
\n" ); document.write( ":
\n" ); document.write( "Each will do a fraction of the job, the two fractions add up to one.
\n" ); document.write( ":
\n" ); document.write( " $\"20%2Fd\"$ + $\"20%2F%284d%29\"$ = 1
\n" ); document.write( "multiply by 4d
\n" ); document.write( "4(20) + 20 = 4d
\n" ); document.write( "100 = 4d
\n" ); document.write( "d = 100/4
\n" ); document.write( "d = 25 days dad alone
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check this, son's time 4(25)
\n" ); document.write( " $\"20%2F25\"$ + $\"20%2F100\"$
\n" ); document.write( ".8 + .2 = 1 \n" ); document.write( "

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