In a certain code language, '476' is written as 'wrong and sharp', '428' is written as 'knife is sharp', and '859' is written as 'right is good'. What is the code for the word 'knife' in that language?

2

Given; In a certain code language, '476' is written as 'wrong and sharp', '428' is written as 'knife is sharp', and '859' is written as 'right is good'. 

So,

4   7   6  =  wrong  and  sharp

4   2   8  =  knife  is  sharp

8   5   9  =  right  is  good

Thus, 

Code for knife is 2