A chemist has two large containers of sulfuric acid solution, with different concentrations of acid in each container. Blending 400 mL of the first solution and 800 mL of the second gives a mixture that is 9% acid, whereas blending 100 mL of the first mixed with 300 mL of the second gives a 7 1 2 % acid mixture. What are the concentrations of sulfuric acid in the original containers