The expression (4 b^{2} c^{-4})^{-5} (5 b^{2} a^{3})^{-4} equals na^rb^sc^t

where n, the leading coefficient, is: ____

and r, the exponent of a, is: ____

and s, the exponent of b, is: ____

and finally t, the exponent of c, is: ____

[NOTE: Your answers cannot be algebraic expressions.]

where n, the leading coefficient, is: ____

and r, the exponent of a, is: ____

and s, the exponent of b, is: ____

and finally t, the exponent of c, is: ____

[NOTE: Your answers cannot be algebraic expressions.]