Walter is mixing cement for his new patio. He knows he needs to use a water-to-cement ratio of $20$ to $30$. What percent of his total mixture is water?

• Hint:

  Write the ratio of water to total mixture as a fraction, then convert to a percentage.

  Step 1:

  $\frac{\text{water}}{\text{mixture}}=\frac{20}{20+30}=\frac{20}{50}=\frac{2}{5}$

  Step 2:

  $\frac{2}{5}=\frac{40}{100}=40\%$

  Answer:

  $40\%$