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Answer:
- drink: $1.35
- sandwich: $4.20
Explanation:
Let d and s represent the cost of a drink and a sandwich, respectively. The two purchases give rise to the equations ...
3d +5s = 25.05
4d +2s = 13.80
Dividing the second equation by 2 gives ...
2d + s = 6.90
Subtracting the first equation from 5 times this, we get ...
5(2d +s) -(3d +5s) = 5(6.90) -25.05
7d = 34.50 -25.05 = 9.45
d = 1.35
The cost of each drink is $1.35.
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Additional comment
Using the simplified 2nd equation, we can find the cost of a sandwich.
s = 6.90 -2d = 6.90 -2.70 = 4.20
The cost of each sandwich is $4.20.