<human>:  Isabella and Alexis went to the mall to buy some pants and dresses. Alexis bought 3 times more pants and dresses than Isabella. If Alexis bought 21 pairs of pants and 18 dresses, how many pairs of pants and dresses did Isabella buy in total?
<bot>: How many pairs of pants did Isabella buy? ** The number of pants Isabella bought is 21 / 3 = <<21/3=7>>7 pairs of pants.
How many dresses did Isabella buy? ** The number of dresses Isabella bought is 18 / 3 = <<18/3=6>>6 dresses.
How many pairs of pants and dresses did Isabella buy in total? ** The total number of pants and dresses Isabella bought is 7 + 6 = <<7+6=13>>13.
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