how do I factor 24x -40xy

Question

I've tried everything to get this down, Thanks

Answer 1

Do a "prime factorization" of each term - that is, factor each of them down to prime numbers:

 

24x = 2*2*2*3*x = 8x*3

 

40xy = 2*2*2*5*x*y = 8x*5y

 

The common factors are shown in orange.  The remaining (uncommon) factors are in black.  Factor out the common numbers (8x):

 

24x-40xy = 8x*3 - 8x*5y = 8x(3 - 5y)