if 4^x+4^x+4^x+4^x+4^x+4^x+4^x+4^x = 1/512, then what is the value of -3/x ?

8 * 4^x = 1/512

=4^x = 1/512*8

=4^x = 1/4096

= 4^x = 1/4⁶

=4^x = 4^-6

x = -6

-3/x 

= -3/-6

= 1/2