Roscoe is a religion professor. During the summer, he spends 3 months in Israel touring historical landmarks. The cost of the summer trip includes $1,300 for airfare, $2,750 for lodging, $1,175 for meals, and $850 for incidental expenses. The following semester he incorporates many of the items he collected and the knowledge he gained from his experiences into his lectures. How much of the travel costs can Roscoe deduct? Explain.