A chemist has a 50 mL beaker of a 20% solution.

a. Write an equation for the concentration, C, of the solution after adding x mL of pure water.

C =  

b. Find the inverse of the function. In other words, write x as a function of C.

x =  

c. Determine how many mL of water should be added to obtain a 10% solution. Round your answer to 1 decimal place.

  mL