<human>:  Aaron and Vanessa were relay race partners on a running team. Aaron was able to run each mile twice as fast as Vanessa, but Vanessa was able to run twice as far as Aaron did. If Vanessa ran 4 miles and Aaron completed his part of the race in 16 minutes, how long in minutes did Vanessa take to complete her part?
<bot>: How far did Aaron run? ** Vanessa ran twice as far as Aaron, so Aaron ran 4 / 2 = <<4/2=2>>2 miles.
How many minutes did Aaron run each mile? ** Aaron took 16 minutes, so he ran each mile in 16 / 2 = <<16/2=8>>8 minutes.
How many minutes did Vanessa take to run each mile? ** Vanessa takes twice as long to run a mile, so she took 8 * 2 = <<8*2=16>>16 minutes for each mile.
How many minutes did Vanessa take to complete her part? ** She ran 4 miles, so she took 4 * 16 = <<4*16=64>>64 minutes to complete her part of the race.
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