Craig purchased a unit comprising one share of stock and one detachable warrant on April 7, 2016. The warrant was exercisable at $21.20 per share, good for five years, and trading at $2 per warrant. On May 17, 2017, Craig exercised his warrant. At that time, the stock was selling for $21.95 per share. How much cash did Craig pay per share of stock on 9/9/17?