Once it is split, you only need to divide the numerical parts $10$ and $25$ by $5$. What do $10 \div 5$ and $25 \div 5$ equal?

After dividing, keep the minus sign between the two terms and keep the powers of $z$ the same as in the original expression.

In a Desmos expression line, type (10z^2 - 25z)/5. Desmos will automatically simplify this expression; compare the simplified form shown by Desmos to the answer choices and select the one that matches exactly.

Start by splitting the fraction into two separate fractions:

This lets you simplify each term separately.

Now divide the coefficients (the numbers in front of $z$) by 5:

• $\frac{10z^2}{5} = 2z^2$ because $10 \div 5 = 2$.
• $\frac{25z}{5} = 5z$ because $25 \div 5 = 5$.

Keep the minus sign between them, since the original expression was $10z^2 - 25z$.

Putting the simplified terms together gives

This matches answer choice D.) $2z^2 - 5z$.