Simplify the expression.
$\frac{y^{27}}{y^9}$

Simplify each expression using the product rule if possible.

$(-4{)}^6(-4)$

Simplify each expression.

$xy\cdot 3x^2$

Simplify each expression.

$(-5a^2)\left(3a^8\right)$

Simplify each expression.

$\left(2s^{3}t\right)\left(3s^4{t}^2\right)$

Simplify the expression. Hint: rewrite using exponents first.

$\frac{64}{16}$

Simplify the expression.

$(-4t{)}^0,t\ne 0$

Use the quotient rule to rewrite each expression, then simplify.

$-\frac{12b^{11}}{4b^7}$

Use the quotient rule to rewrite each expression, then simplify.

$\frac{9x^2{y}^8}{3x{y}^2}$