Question 75045
Let x = the required number of ounces of 15% saline solution.  
Change the percentages to their decimal equivalents:
15% = 0.15
5% = 0.05
10% = 0.1
From the problem description, you can write:
(0.15)x + (0.05)(30) = (0.1)(x+30) Simplify and solve for x.
0.15x+1.5 = 0.1x+3 Combining like-terms, you subtract 0.1x from both sides.
0.05x+1.5 = 3 Now subtract 1.5 from both sides.
0.05x = 1.5 Finally, you divide both sides by 0.05
x = 30
You will need to add 30 ounces of a 15% saline solution to 30 ounces of a 5% saline solution to obtain 60 ounces of a 10% saline solution.