Fractorise:
`x (a -3) + y ( 3 -a)`

Answer

To factorise the expression \( x(a - 3) + y(3 - a) \), we will follow these steps:

### Step 1: Rewrite the expression
We start with the expression:
\[ x(a - 3) + y(3 - a) \]

### Step 2: Rearrange the second term
Notice that \( 3 - a \) can be rewritten as \( -(a - 3) \):
\[ x(a - 3) + y(-(a - 3)) \]
This simplifies to:
\[ x(a - 3) - y(a - 3) \]

### Step 3: Factor out the common term
Now, we can see that both terms contain the common factor \( (a - 3) \):
\[ (a - 3)(x - y) \]

### Final Answer
Thus, the factorised form of the expression \( x(a - 3) + y(3 - a) \) is:
\[ (a - 3)(x - y) \]

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