Answer :

1/4 since 2/3 times 1/2 is 1/3 and if u multiply that by 3/4, the result is 3/12 which can be simplified to 1/4
2/3 x 1/2 x 3/4

Multiply the numerators.. ( 2 x 1 x 3 = 6 )
Multiply the denominators.. ( 3 x 2 x 4 = 24 )

6/24 <---- simplify this fraction 

  6 x 6               1     
-----------      =    -----        
 24 x 6              4  

The final answer is 1/4  :)