Answer: a drink costs $5.5
Step-by-step explanation:
Let x represent the cost of one bag of popcorn.
Let y represent the cost of one drink.
Kylie spends a total of $125.50 on 12 bags of popcorn and 7 drinks. This means that
12x + 7y = 125.50 - - - - - - - - - - 1
Amelia spends a total of $87.50 on 6 bags of popcorn and 8 drinks. This means that
6x + 8y = 87.50 - - - - - - - - - -- - - 2
Multiplying equation 1 by 1 and equation 2 by 2, it becomes
12x + 7y = 125.50
12x + 16y = 175
Subtracting, it becomes
- 9y = - 49.5
y = - 49.5/ - 9
y = 5.5
Substituting y = 5.5 into equation 2, it becomes
6x + 8 × 5.5 = 87.50
6x + 44 = 87.5
6x = 87.5 - 44 = 43.5
x = 43.5/6 = 7.25