Y varies directly as the cube root of x.if x =27,then y=2?

y varies directly with the cube root not the cube as one answer indicated 
so 
it means if c is a constant. 

y =  cx^(1/3)   
2 = c(27)^(1/3) =  3c 
c =  2/3  
means this is the equation,  
y = (2/3)x^(1/3)     
checking 
y = (2/3) (27)^(1/3) = (2/3)(3)  =2  

So you forgot to ask a question. 
so the equation is 
y = (2/3)x^(1/3)    or write it with cube root radical (which 
is easier with Paper and pencil. 

Now, add a question to your question
so it can be answered. 

Statement:  Y varies directly as the cube root of x 
Statement:  If x = 27,   then y = 2 
Now add a question if you want. 

Hint:
Y varies directly as the cube root of x
so
y = k * (cube root of x) , with constant k ≠ 0

Translate the sentence into:
y=cx^3 where c is a nonzero real constant.

Sub x=27, y=2:
2=c(27)^3 => c=2/(27^3)