Lehman Brothers, Inc. (LBI), wrote a letter to Mary Dragon offering her employment as LBI's "Business Chief Administrative Offic in Its Faed Income Division." The offer included a salary of $150,000 per year and an annual "minimum bonus of $350,000. The letter stated that the bonus would be paid unless Ortegon resigned or was terminated for certain causes. In other words, the bonus was not a 'signing' bonus—it was dearly tied to her performance on the job. Dragon accepted the offe . Before she started work, however, LBI rescinded it. Later, LBI filed for bankruptcy in a federal court. Dragon filed a daim with the court for the amount of the bonus on the ground that LBI had breached its contract with her by not paying it. Can extrinsic evidence be admitted to interpret the meaning of the bonus term? Explain.