Alexa and the Tea Plantation
05AB1E, 20 bytes

WU|vy#Â‚ø€¥˜Ä2ä`OX*,


Explanation

WU                    # store minimum cost in X
  |v                  # for each testcase
    y#                # convert to list split on spaces
      Â‚ø             # zip with its own reverse
         €¥           # deltas of each pair
           ˜Ä         # deep flatten and take absolute value
             2ä       # split into 2 pieces
               `      # flatten (leaves the smaller piece on top of the stack)
                O     # sum
                 X*   # multiply with minimum cost
                   ,  # print


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