A chef is going to use a mixture of two brands of Italian dressing. The first brand contains 7 vinegar, and the second brand contains 12 vinegar. The chef wants to make 390 milliliters of a dressing that is 11 vinegar. How much of each brand should she use

78 ml of 7% vinegar and 312 ml of 12% vinegar.

Step-by-step explanation:

Let x represent ml of 7% vinegar brand and y represent ml of 12% vinegar brand.    

We have been given that chef wants to make 390 milliliters of the dressing. We can represent this information in an equation as:

We are also told that 1st brand 7% vinegar, so amount of vinegar in x ml would be .

The second brand contains 12 vinegar, so amount of vinegar in y ml would be .

We are also told that the chef wants to make 390 milliliters of a dressing that is 11% vinegar. We can represent this information in an equation as:

Upon substituting equation (1) in equation (2), we will get:

Therefore, the chef should use 78 ml of the brand that contains 7% vinegar.

Upon substituting in equation (1), we will get:

Therefore, the chef should use 312 ml of the brand that contains 12% vinegar.

33/100 is what i got