The three sides of a triangle are $\left(3a-7b+8c\right)$ cm, $\left(a-9b+10c\right)$ cm and $\left(-9+8b-11c\right)$ cm. Find the perimeter of the triangle.

Find the perimeter of the rectangle from the given figure.

Subtract:

$13x^2 \text{from} 7x^2$

Subtract:

$\left(2a-7b\right)$ from $\left(a+10b\right)$

Subtract $\left(a^3+3a^{2}b-b^3\right)$ from $\left(3a^3-4a^2{b}^2-7b^3\right)$.

Subtract $11x^2+16xy-9y^2$ from $15x^2-6xy+3y^2$.

Simplify: $\left(11x^2+17xy-4y^2\right)-\left(-6x^2+4xy-9y^2\right)$.

From the sum of $a^2-7a+10$ and $3a^2+4a-15$, subtract $2a^2+a-9$.

What must be added to $7x^2-14x+32$ to get, $9x^2-10x-15$?