2^x=4^y=8^z......................................................given
2^x=2^(2y)=2^(3z)
x=2y=3z
x.............................................................................(i)
y=x/2.....................................................................(ii)
z=x/3....................................................................(iii)
[1/2x+1/4y+1/4z]..............................................given
{(1/2x)+[1/4(x/2)]+[1/4(x/3)]........................from (i),(ii),(iii)
Simplify
x=7/16
Ans is 7/16