(b) Factorise: \( \begin{array}{llll}\text { (1) } & x(a+b)+y(a+b) & \text { (2) } & k(x+y)+p(x+y) \\ \text { (3) } & 3 p(q+r)-4 m(r+q) & \text { (4) } & 7 k(m-3 n)-3 p(m-3 n) \\ \text { (5) } & (x-y)^{2}-3(x-y) & \text { (6) } & (a+c)^{4}+(a+c)^{5} \\ \text { (7) } & (m-n)^{6}+(m-n)^{2} & \text { (8) } & 7 x(m-3 n)-4 y(3 n-m) \\ \text { (9) } & 7 x(m-3 n)+4 y(3 n-m) & \text { (10) } & 7 x(m+3 n)+4 y(-m-3 n) \\ \text { (11) } & 2 x(3 p+q)+4 y(-q-3 p) & \text { (12) } & (a-b)-(p b-p a) \\ \text { (13) } & 4 x\left(a^{3}-2\right)+\left(2-a^{3}\right) & \text { (14) } & 2 x^{2}(3 a-b)-12 x(b-3 a) \\ \text { (15) } & (a-3 b)-c(3 b-a)+d(3 b-a)\end{array} \)

Here are the factorised forms of the given expressions: 1. \( x(a + b) + y(a + b) = (a + b)(x + y) \) 2. \( k(x + y) + p(x + y) = (x + y)(k + p) \) 3. \( 3p(q + r) - 4m(q + r) = (q + r)(3p - 4m) \) 4. \( 7k(m - 3n) - 3p(m - 3n) = (m - 3n)(7k - 3p) \) 5. \( (x - y)^2 - 3(x - y) = (x - y)(x - y - 3) \) 6. \( (a + c)^4 + (a + c)^5 = (a + c)^4 (1 + a + c) \) 7. \( (m - n)^6 + (m - n)^2 = (m - n)^2 (1 + (m - n)^4) \) 8. \( 7x(m - 3n) - 4y(3n - m) = (m - 3n)(7x + 4y) \) 9. \( 7x(m - 3n) + 4y(3n - m) = (m - 3n)(7x - 4y) \) 10. \( 7x(m + 3n) + 4y(-m - 3n) = (m + 3n)(7x - 4y) \) 11. \( 2x(3p + q) + 4y(-q - 3p) = 2(3p + q)(x - 2y) \) 12. \( (a - b) - (p b - p a) = (1 + p)(a - b) \) 13. \( 4x(a^3 - 2) + (2 - a^3) = (a^3 - 2)(4x - 1) \) 14. \( 2x^2(3a - b) - 12x(b - 3a) = 2x(3a - b)(x + 6) \) 15. \( (a - 3b) - c(3b - a) + d(3b - a) = (a - 3b)(1 + c - d) \) These are the fully factorised forms of the provided expressions.