Monica travels from her office in Boston to Lisbon, Portugal, on business. Her absence of 13 days was spent as follows: Thursday Depart for and arrive at Lisbon Friday Business transacted Saturday and Sunday Vacationing Monday through Friday Business transacted Saturday and Sunday Vacationing Monday Business transacted Tuesday Depart Lisbon and return to office in Boston

1. For tax purposes, how many days has Monica spent on business?

2. What difference does it make?

3. Could Monica have spent more time than she did vacationing on the trip without loss of existing tax benefits? Explain.