Use the formula C = pi * d
Let x be a variable.
Using the ratio and the given number of 117, we can create the following formula:
1x + 3x + 9x = 117, where 3x is the cups of onion
Simplify this equation.
13x = 117
Divide both sides by 13
x = 9
We want to solve for 3x, so multiply both sides by 3
3x = 27
As I started earlier, 3x is how many cups of onions is needed; thus, 27 is our answer. Hope this helps! :)
Answer:

Step-by-step explanation:
We have the equation 
In order to solve for x, we need to get all of the x's to one side and everything else to the opposite side

First, we can add 1 to each side

Now, we can add x to each side

Next, we can divide each side by 2

And here is our answer.