To simplify the expression (1/5)^-2+5^-3/5^-4-2015, we need to follow the order of operations, which is parentheses, exponents, multiplication and division from left to right, and addition and subtraction from left to right.

Step 1: Simplify exponents.
(1/5)^-2 = 5^2 = 25
5^-3 = 1/5^3 = 1/125
5^-4 = 1/5^4 = 1/625

Step 2: Simplify the expression.
25 + 1/125 / 1/625 - 2015
= 25 + 625 - 2015
= 650 - 2015
= -1365

Therefore, the simplified expression is -1365.