Answer:
Cost of each large soft drink is $3.00 and Cost of each Large bucket of popcorn is $4.50.
Step-by-step explanation:
Let the Cost of each large soft drink be x.
Also Let the Cost of each Large bucket of popcorn be y.
Number of people = 3
Money Spend on popcorn and soft drink = $22.50
Hence we can say that;

Next week three people traveled again.
Each ticket was bought = $8.00
Number of tickets bought = 3
Money spend on tickets = 
Total return trip = $37.50
Also they each get a large soft drink, but they share one large bucket of popcorn
Cost of Soft drink = 3x
Cost of popcorn = y
Now Total return trip is equal to sum of Money spend on tickets and Cost of soft drink and Cost of popcorn.
Hence equation can be framed as;

Now Subtracting equation 2 from equation 1 we get;

Now substituting the value of y in equation 1 we get;

Hence Cost of each large soft drink is $3.00 and Cost of each Large bucket of popcorn is $4.50.