Clare would need 80 of fish, (1/3 of 240 is 80.)
Ian would need 200g of butter (If you find the amount of each ingredient needed for a one person-pie, and multiply them by the amount of people you need to feed, you will get your answer.)
We know that 80g of butter is used for 6 people, so by dividing 80 by 6, we know that for a one person-pie, you would need 13.33g of butter. Multiply 13.33 by 15 to find out how many grams of butter he would need for a pie for 15 people.
When doing this, we would have to first straight them all out, and as we see above, they are just all over the place, and then, we would have to set them up as a sequence.
![\left[\begin{array}{ccc}5x2 + 5y2 - 20x + 30y + 40 = 0\end{array}\right]](https://tex.z-dn.net/?f=%20%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D5x2%20%2B%205y2%20-%2020x%20%2B%2030y%20%2B%2040%20%3D%200%5Cend%7Barray%7D%5Cright%5D%20)
would be our first step in this problem mainly because it contains the most terms in this aspect.
Then we would then

, then,

.
These would only be our first 3 part of the sequence in this aspect.
The others would then be the following:

Thus, as we would have one more afterward, our last part of the sequence would then be the following.

I hope this was found helpful!
Let the youngest sister be n years
Lana will be 2n years, as her youngest sister is half her age
The age of the twins separately will be 2n-2 as they are 2 years younger than Lana
So, the equation looks like this:
n + 2n + 2(2n-2) = 45
Now solve for n:
3n + 4n - 4 = 45
7n - 4 = 45
7n = 49
n = 7
So the youngest sister is 7, Lana is 14 and the twins are 12. 14 + 12 + 12 + 7 =45