code: def test_negative_decimal_multiplication(self):
      statement = Statement(text="What is -100.5 * 20?")
      response = self.adapter.process(statement)
      self.assertEqual(response.text, "-100.5 * 20 = -2010.0")
      self.assertEqual(response.confidence, 1)
  
imports: from tests.base_case import ChatBotTestCase
  from chatterbot.logic import MathematicalEvaluation
  from chatterbot.conversation import Statement
label_desc: Use image node_id 15 for calling the MathematicalEvaluationTests obj's underlying member method code with example usage: obj.test_negative_decimal_multiplication() without return types