Andrea needs 3/8 ounce of vanilla for her cookie recipe. If 1 milliliter is approximately 0.03 ounce, write an expression to determine the number of millimeters of vanilla Andrea needs for her cookie recipe.

3/8 times 1/.03 = amount of vanilla in millimeters.

To determine the number of milliliters of vanilla Andrea needs for her cookie recipe, we need to find the equivalent amount in milliliters using the given conversion factor between ounces and milliliters.

First, let's convert the amount of vanilla needed to ounces. We know that Andrea needs 3/8 ounce of vanilla.

Next, we use the conversion factor given in the question: 1 milliliter is approximately 0.03 ounce.

To convert from ounces to milliliters, we can set up a proportion:

(3/8 ounce) / (1) = (x milliliters) / (0.03 ounce)

Cross-multiplying the proportion, we get:

(3/8) * (0.03) = x

Simplifying, we have:

0.09/8 = x

Therefore, the expression to determine the number of milliliters of vanilla Andrea needs for her cookie recipe is:

x = 0.09/8 milliliters