Question

42x ​5 ​​ y ​4 ​​ =(−7x ​3 ​​ y)(B)

Answer 1

This is my very own step-step solution:

Step 1:
Rearrange the equation by subtracting what is to the right of the equal sign from both sides of the equation : 

                42*x^5*y^4-((-7*x^3*y)*(b))=0 
Step 2:Equation at the end of step  1  :
 
               ((42•(x5))•(y4))-((0-(7x3•y))•b) = 0

Step 3:Pulling out like terms :  

   42x5y4 + 7x3yb  =   7x3y • (6x2y3 + b) 

The correct is: 7x3y • (6x2y3 + b) = 0 

Quick Side Note:
Binomial can not be factored as the difference of two perfect cubes

I hope this helps a little!

Hope you have a great day!