Factorise 3(3x-y)-(y-3x)

Answer:
4(3x-y)
Step-by-step explanation:
Given:
[tex]\displaystyle \large{3(3x-y)-(y-3x)}[/tex]
To factor this kind of expression, first, find the common factor.
[tex]\displaystyle \large{3(3x-y)-(-3x+y)}\\\displaystyle \large{3(3x-y)+(3x-y)}[/tex]
Notice that in the expression, we have both same (3x-y). Therefore, (3x-y) is our factor.
Let u = 3x-y
[tex]\displaystyle \large{3u+u}\\\displaystyle \large{4u}[/tex]
Change u back to 3x-y:
[tex]\displaystyle \large{4(3x-y)}[/tex]
Therefore, the factored expression is 4(3x-y).