18. Ms. Acosta works in the lab at a pharmaceutical company. She needs to make 21 liters of a 32% acid solution to
test a new product. Her supplier only ships a 28% and a 35% solution. Ms. Acosta decides to make the
32% solution by mixing the 28% solution with the 35% solution. How much of the 28% solution will Ms. Acosta
need to use?
A. 6L
B. 9L
C. 12L
D. 21L