Multiply

$(10-3x)(7+x)$

Multiply

$(11x+2x)(8-2y)$

Multiply

$(a+by)(4a-6y)$

Multiply

$\left(2x^{2}y-y^2\right)\left(3x-5y\right)$

Multiply

$\left(\frac{x}{2}-\frac{y}{3}\right)\left(\frac{2x}{3}-\frac{3y}{5}\right)$

Multiply

$\left(\frac{2a^2}{9}-\frac{1}{7}\right)\left(\frac{3a}{5}-\frac{2}{5}\right)$

$2a\times 3b=$_____

$6ab÷2a=$_____