Question 1018787
Okay from
10ax - 5ay + 2bx - by
Do you notice that the first two terms have a common factor?  And that it is 5a?  We factor that out and get
5a(2x - y) + 2bx - by
Do you see how the 3rd and 4th terms have b in common?  We factor the b out...
5a(2x - y) + b(2x - y)
Now, do you see how both terms have (2x - y) in common?  We factor that out...
(2x - y)(5a + b)
and we are done.