The answer here is that a soft drink costs $1.50 and fries cost $2. Here is how you can get that answer:

Let's let S be soda and F be fries.

We know that 2S + F = 5 because of your first statement. Because of your second statement, we know that 2S + 2F = 7.

So now we can substitute. In the first equation, let's find for F. F = 5 - 2S.

Now we can plug that into the second equation and we now have

2S + 2 (5 - 2S) = 7

2S + 10 - 4S = 7

-2S = -3

S = 1.5

Now we plug this value for S back into one of the equations.

3 + F = 5

F = 2

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