There is a beaker of 3.5% acid solution and a beaker of 6% acid solution in the science lab. Mr. Larson needs 200ml of 4.5% acid solution for an experiment. How many of each solution should he combine?

Below are the choices:

A. 80 mL of the 3.5% solution and 120 mL of the 6% solution

B. 120 mL of the 3.5% solution and 80 mL of the 6% solution

C. 140 mL of the 3.5% solution and 60 mL of the 6% solution

D. 120 mL of the 3.5% solution and 80 mL of the 6% solution

Let fraction of 3.5% in final solution be p.

p * 3.5 + (1 - p) * 6 = 4.5

3.5p + 6 - 6p = 4.5

2.5p = 1.5

p = 3/5

3/5 * 200 = 120

Therefore the answer is B. 120 ml of 3.5% and 80 ml of 6%.