Three pounds of beef cost $4 x 3 = $<<4*3=12>>12.
Mary's mother paid $12 + $1 = $<<12+1=13>>13 for the beef and oil.
Hence, the 2-pound chicken cost $16 - $13 = $<<16-13=3>>3.
There are 1 (Mary) + 2 friends = <<1+2=3>>3 people who will split the $3 cost.
Therefore, each of them will pay $3/3 = $<<3/3=1>>1.
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