Factorise the following expressions.

$10xy-15x^2{y}^2$

Factorise the following expressions.

$20x^{2}y+30xyz$

On factorising the following expression $8a^4{b}^2{c}^3+12a^2{b}^2{c}^3$ we get $4a^2{b}^2{c}^3\left(2a^2+k\right)$, find the value of $k$

On factorising the following expression $3x^3-x^2+x$ we get $x\left(3x^2-x+k\right)$, find the value of $k$

On factorising the following expression $x^2-xy+x{y}^2$ we get $x\left(x-y+y^k\right)$, find the value of $k$

If the factors of the expression $6x^2-9x^{2}y+12x{y}^2$ is of the form $ax\left(bx-cxy+d{y}^2\right)$, then find the value of $a+b+c+d.$

On factorising the following expression $5x^4-10a^2{x}^2-15a^2{x}^3$ we get $k{x}^2\left(x^2-2a^2-3a^{2}x\right)$, find the value of $k$

On factorising $3x^3{y}^2+9x^{2}y+12xy$ we get $3xy\left(x^{k}y+3x+4\right)$, find the value of $k$.

If $28x^3{y}^3-21x^4{y}^3-14x^5{y}^5$ can be factorised in the form of $a{x}^3{y}^3\left(b-cx-d{x}^m{n}^n\right)$, then find the value of $\left(a+b+c+d+m+n\right)$.