Okay, here we have this:
Considering the provided information, we are going to calculate the requested value, so we obtain the following rule of three:
[tex]\begin{gathered} \frac{x}{35mL\text{ of water}}=\frac{250g\text{ of plaster}}{100g\text{ of plaster}} \\ x=\frac{250g\text{ of plaster}}{100g\text{ of plaster}}\cdot35mL\text{ of water} \end{gathered}[/tex]Solving for x:
[tex]\begin{gathered} x=2.5\cdot35mL\text{ of water} \\ x=87.5mL\text{ of water} \end{gathered}[/tex]Finally we obtain that 87.5mL of water should be used for 250g of plaster.
