Algebra multiplication squares

This task is about what happens to indices when algebraic expressions are multiplied.
a)
The squares in the box below can be filled in so that each row and column equals x3y4 when the expressions in it are multiplied together.
 
   
Fill in the boxes in the order they are numbered. 
 
 
b) Fill in the squares in the box below so that each row and column equals x6y3 when the expressions in that row or column are multiplied together.