Foreign exchange gain\loss

Dear Sir,

I want to know the treatment of foreign exchange in books of accounts for the undergiven.

1.I made an invoice of say $5000 on 25th May'13 when the rate was 1$=60. But when I recieved the amount on May'14 from the party the rate of exchange deviated to 1$=62. 

2. I made an invoice of say $5000 on 25th May'13 when the rate was 1$=60. But when I recieved the amount on August'13 from the party the rate of exchange deviated to 1$=62.