Winston's soup recipe make 6 servings and uses 4 carrots and 2 potatoes. how many will winston need for 15 servings

Hello there!
We have the following equation:
c + p = 15 (c = carrots, p = potatoes)
Previously, we had this equation:
2 + 4 = 6.
2 is 1/3 of 6, and 4 is 2/3 of 6. The sum of these two fractions make a whole.

Let's apply this rule to 15 servings.
Since we are looking for thirds, divide 15 by 3 to solve for 1/3, or "p".
15 / 3 = 5
We have 5 potatoes.

Now, we must remember that the amount of carrots is twice the amount of potatoes.
Divide 15 by 3, then multiply that quotient by 2.
15 / 3 = 5
5 * 2 = 10

We have 10 carrots.

Your final answer is:
Winston will need 5 potatoes and 10 carrots.

I hope this helps!