Answer:
C
Explanation:
the midsegment is equal to half the sum of the parallel bases, that is
(AB + CD) = MN ( substitute values )
(AB + 14.3) = 21.1 ( multiply both sides by 2 to clear the fraction )
AB + 14.3 = 42.2 ( subtract 14.3 from both sides )
AB = 27.9 cm