Answer:
He should have exchanged the dollars for real in January 2016 to maximize his Brazilian spending. The exchange rate in January will result to highest Real (BRL) of R$<em>59,463.00</em>
Explanation:
To arrive at R$ equivalent of $15,000 on monthly basis, since  BRL=1.00 USD, multiply R$ exchange rate each month by $15,000.
For January,  3.9642*15,000= R$59,463.00 
      February  3.8402*15,000= $57,603.00, etc.
Solution  	
S/N	Month      BRL=1.00 USD          BRL Equivalent(R$)
1	January              3.9642              59,463.00 
2	February            3.8402               57,603.00 
3	March                 3.6086               54,129.00 
4	April                    3.6851                55,276.50 
5	May                     3.5843               53,764.50 
6	June                    3.5493               53,239.50 
7	July                      3.2331               48,496.50 
8	Aug-08                3.2312               48,468.00