Which relationship shows a quadratic variation?

i believe the answer is the top one, correct me if im wrong.

$5

Step-by-step explanation:

Let the cost of one burger be $b while the cost of one small fries be s

2 burgers and 2 small fries cost $14

This means that;

2b + 2s = 14

divide both sides by 2

b + s = 7 •••••••• (i)

Three burgers and four small fries cost $23

Mathematically;

3b + 4s = 23 •••••••• (ii)

From i , we can see that s = 7- b

we can now substitute this into equation ii

3b + 4(7-b) = 23

3b + 28 -4b = 23

4b -3b = 28 -23

b = $5

one burger costs $5