Simplify -(15w^0u^-1)/(5u^3)

$- \frac{15 w^{0} u^{- 1}}{5 u^{3}}$

Move $u^{- 1}$ to the denominator using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$- \frac{15}{5 u^{3} u}$

Multiply $u^{3}$ by $u$ by adding the exponents.

Move $u$ .

$- \frac{15}{5 (u \cdot u^{3})}$

Multiply $u$ by $u^{3}$ .

Raise $u$ to the power of $1$ .

$- \frac{15}{5 (u^{1} u^{3})}$

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$- \frac{15}{5 u^{1 + 3}}$

Add $1$ and $3$ .

$- \frac{15}{5 u^{4}}$

Cancel the common factor of $15$ and $5$ .

Factor $5$ out of $15$ .

$- \frac{5 \cdot 3}{5 u^{4}}$

Cancel the common factors.

Factor $5$ out of $5 u^{4}$ .

$- \frac{5 \cdot 3}{5 (u^{4})}$

Cancel the common factor.

$- \frac{5 \cdot 3}{5 u^{4}}$

Rewrite the expression.

$- \frac{3}{u^{4}}$