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.

ou would have 12 of each

c.

step-by-step explanation:

because first you have to add the 4x, 9x, and the 7x together and you get 20x and then you add the last numbers up and you get 5and then you put the subtraction sign in there and that's how you get the answer.