Question 965418
working together john and bob can paint a house in 3 1/2 hours. working alone bob can do the job in 6 hours. how long does it take for john to do the job alone?
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let x=hours john can do the job alone
1/x=his work rate
1/6=bob's work rate
1/3.5=work rate working together
sum of indv. work rates=work rate working together
..
1/x+1/6=1/3.5
1/x=1/3.5-1/6
lcd:6*3.5*x=21x
21=6x-3.5x
2.5x=21
x=8.4
 how long does it take for john to do the job alone? 8.4 hrs