A scientist has a container of 2% acid solution and a container of 5% acid solution. How many fluid ounces of each concentration should be combined to make 25 fl oz of 3.2% acid solution?

Let 'a' be the number of ounces of 2%-solution in the 25-ounce mixture and 'b' be the number of ounces of 5%-solution in the 25-ounce mixture.Since, fluid ounces of each concentration should be combined to make 25 fl oz.So, a+b=25 (Equation 1)And, a container of 2% acid solution and a container of 5% acid solution should be combined to make 25 fl oz of 3.2% acid solution.So, a of 2% + b of 5% = 3.2% of 25[tex] (a \times \frac{2}{100})+(b \times \frac{5}{100})= 25 \times \frac{3.2}{100} [/tex][tex] (0.02a)+(0.05b)= 0.8 [/tex]Multiplying the above equation by 100, we get[tex] 2a+5b=80 [/tex] (Equation 2)Substituting the value of a=25-b in equation 2, we get[tex] 2(25-b)+5b=80 [/tex][tex] 50-2b+5b=80 [/tex][tex] 50+3b=80 [/tex][tex] 3b=30 [/tex][tex] b=10 [/tex]Since, a=25-ba= 25-10a=15.So, 15 fluid ounces of 2% solution combined with 10 ounces of the 5% solution to create a 25-ounce mixture at 3.2% concentration of acid.