Answer:
the prices were $0.05 and $1.05
Step-by-step explanation:
Let 'a' and 'b' represent the costs of the two sodas. The given relations are ...
a + b = 1.10 . . . . the total cost of the sodas was $1.10
a - b = 1.00 . . . . one soda costs $1.00 more than the other one
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Adding these two equations, we get ...
2a = 2.10
a = 1.05 . . . . . divide by 2
1.05 -b = 1.00 . . . . . substitute for a in the second equation
1.05 -1.00 = b = 0.05 . . . add b-1 to both sides
The prices of the two sodas were $0.05 and $1.05.
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<em>Additional comment</em>
This is a "sum and difference" problem, in which you are given the sum and the difference of two values. As we have seen here, <em>the larger value is half the sum of the sum and difference</em>: a = (1+1.10)/2 = 1.05. If we were to subtract one equation from the other, we would find <em>the smaller value is half the difference of the sum and difference</em>: b = (1.05 -1.00)/2 = 0.05.
This result is the general solution to sum and difference problems.
