$\left(+7\right)\left(-11\right)\left(+5\right)$

$\left(9+11b\right)\left(9-11b\right)$

$9a^2b-3xy-15a^2b+8xy-5a^2b+4xy$

$18-\left(3+-5-7+9\right)$

$\left(x-2\right)\left(x^6-2x^5-4x^4-8x^3+16x^2-42x+64\right)$

$-3+2-\left(-3+0\right)+1$

$\left(-xy+\frac{5}{8}\right)\left(-xy+\frac{3}{4}\right)$