How to fill in 3 / 4 1 / 2 1 / 3 () 4 / 27 (),

How to fill in 3 / 4 1 / 2 1 / 3 () 4 / 27 (),

Multiply the previous number by 2 / 3 to get the next one
3/4,1/2,1/3,(2/9),4/27,(8/81)