Question 1138740
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Since he works twice as fast as she does, when working together he does 2/3 of the work and she does 1/3.<br>
So in 8 minutes working together, he does 2/3 of the job.  To do the remaining 1/3 of the job himself, he needs to work half of another 8 minutes, or 4 minutes more.  So he can do the job alone in 12 minutes.<br>
And since he works twice as fast as she does, the time it would take her to do the work alone is 24 minutes.