Factorise:

$3x+12$

Factorise:

$4m-20$

Factorise:

$8x^2-64x$

Factorise:

$3y^2-51xy$

Factorise:

$x^2+19xy$

Factorise:

$15x^2-45x^{2}y$

Factorise:

$77x^6{y}^8-33x^3{y}^{10}$

Factorise:

$121x^2+11y^2{x}^5$

Factorise:

$4a\left(7x-27\right)-3b\left(7x-27\right)$