The cost for 10 ounces of organic blueberries is [tex] \$2.70 [/tex]. Which equation can be used to determine [tex] x [/tex], the cost in dollars for 30 ounces of organic blueberries?

A. [tex] \frac{10}{2.7} = \frac{x}{30} [/tex]

B. [tex] \frac{27}{10} = \frac{30}{x} [/tex]

C. [tex] \frac{10}{27} = \frac{30}{x} [/tex]

D. [tex] \frac{27}{30} = \frac{x}{10} [/tex]

To determine the cost of 30 ounces of organic blueberries given that 10 ounces cost [tex]$2.70, we can use a proportion. Let's break it down step-by-step:

1. Understand the given information:
- 10 ounces of blueberries cost $[/tex]2.70.

2. Set up a proportion to find the cost for 30 ounces:
- Since 10 ounces cost [tex]$2.70, you want to find the cost, $ x $, for 30 ounces.
- The proportion is set up by comparing the known and unknown values evenly:

\[
\frac{\text{Cost of 10 ounces}}{\text{10 ounces}} = \frac{x}{\text{30 ounces}}
\]

3. Plug in the known values:
- We know the cost is $[/tex]2.70 for 10 ounces, so we plug that into the proportion:

[tex]\[
\frac{2.70}{10} = \frac{x}{30}
\][/tex]

4. Cross-multiply to solve for [tex]$ x $[/tex]:
- By cross-multiplying, you create an equation that allows you to solve for [tex]$ x $[/tex]:

[tex]\[
2.70 \times 30 = 10 \times x
\][/tex]

[tex]\[
81 = 10x
\][/tex]

5. Solve for [tex]$ x $[/tex]:
- Divide both sides of the equation by 10 to find [tex]$ x $[/tex]:

[tex]\[
x = \frac{81}{10}
\][/tex]

[tex]\[
x = 8.10
\][/tex]

So, the cost for 30 ounces of organic blueberries is $8.10.

Based on the options provided, the correct equation from the original question is option C:

[tex]\[
\frac{10}{27} = \frac{30}{x}
\][/tex]

This correctly represents the relationship needed to solve for [tex]$ x $[/tex] in this situation.