The expression $(2 b^{1} c^{-4})^{4} (5 b^{0} a^{-4})^{3}$ 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: The value for $n$ may be given as a fraction or as a just number. All other values must be given as just numbers (no arithmetic expressions).