The given expression is
(4^-3)^7
We would apply the law of exponents which is expressed as
(a^- b) = 1/a^b
We can see that
a = 4
b = - 3
Writing it using a single positive exponent, it becomes
4^ - 3 = 1/4^3 = 1/64
The final expression would be
(1/64)^7