Cost of case of lemonade is $14 and cost of case of fruit punch is $4
Solution:
Let the cost of fruit punch be $ m and cost of lemonade be $ n
Aidan sold 6 cases of fruit punch and 4 cases of lemonade for a total of $80. Thus we get,

6m + 4n = 80 ----- eqn (1)
Layla sold 6 cases of fruit punch and 5 cases of lemonade for $94.

6m + 5n = 94 ------ eqn (2)
So, now, subtract (1) from (2)
(2) ⇒ 6m + 5n = 94
(1) ⇒ 6m + 4n = 80
(-) -------------------------
0 + n = 14
n = 14
Now, substitute "n" value in (1)
6m + 4(14) = 80
6m + 56 = 80
6m = 24
m = 4
Hence, cost of case of lemonade is $14 and cost of case of fruit punch is $4