A chef is going to use a mixture of two brands of Italian dr

A chef is going to use a mixture of two brands of Italian dressing. The first brand contains 5% vinegar, and the second brand contains 11 % vinegar. The chef wants to make 270 milliliters of a dressing that is 9% vinegar. How mu Ch of each brand should she use?

Solution

Let x be the quantity of 5% vinegar
5% -------------------------    11%   ---------------------- 9% mix
x ---------------------------    270 - x   ---------------------    270
0.05x + 0.11*(270 - x) = 0.09 * 270
0.05x + 29.7 - 0.11x = 24.3
- 0.06x = 24.3 -29.7
-0.06x = - 5.4

0.06x = 5.4
x = 5.4 / 0.06
x = 90 ml