Really easy math question!

a. 146 ≤ 9c + 10

Explanation:
Step 1 - Find Out What Symbol We Will Be Using
Natalies budget is $146. This means she can spend less than or exactly $146 on yoga training. So, we will be using the less than or equal to symbol. It looks like this: ≤.

Step 2 - Eliminate Incorrect Options
Now that we know the symbol will look like ≤, we can eliminate options d and b.

Step 3 - Find Out Which Is The Dependent Variable
Natalie is going to buy a yoga mat which only costs $10. She is also going to join yoga classes which costs $9 per class. Since, the total cost of yoga classes depends on how many classes she takes, this is the dependent variable.

Step 4 - Write The Equation Using The Information Gathered
146 ≤ 9c + 10