actorise fully \( 3 a x+3 a y-x-y \)

To factorise the expression \( 3ax + 3ay - x - y \), we can group the terms effectively. Start by grouping the first two terms and the last two terms: \[ (3ax + 3ay) - (x + y) \] Now, we can factor out common factors from each group. From the first group, we can factor out \( 3a \), and from the second group, we can factor out \( 1 \): \[ 3a(x + y) - 1(x + y) \] Now, we see that \( (x + y) \) is a common factor, so we can factor that out: \[ (x + y)(3a - 1) \] Thus, the fully factorised form of the expression is: \[ (x + y)(3a - 1) \]