Answer:
4
Step-by-step explanation:
[tex]x - 2y = 1\\\\\implies x=1+2y[/tex]
If [tex]y=-1[/tex]
[tex]\implies x=1+2(-1)=-1[/tex]
[tex](4^x)^y=(4^{-1})^{-1}=4^1=4[/tex]
