Bunuel wrote:
At a certain stand, all soft drinks cost the same and all sandwiches cost the same. How much does 1 sandwich cost at the stand?
(1) At the stand, 1 sandwich and 2 soft drinks cost a total of $3.15.
(2) At the stand, 3 sandwiches and 1 soft drink cost a total of $5.70.
Let soft drinks cost x each and sandwiches cost y each... We want to know y...
We can see that each statement gives us two unique equations with two variables, hence we can find x and y when two statements are combined..SUff Lets check each statement..
(1) At the stand, 1 sandwich and 2 soft drinks cost a total of $3.15.
y+2x=3.15...(i)
(2) At the stand, 3 sandwiches and 1 soft drink cost a total of $5.70.
3y+x=5.70....(ii)
Combined..
Multiply (ii) by 2 and subtract (i) from it..
\(2(3y+x)-(y+2x)=2*5.70-3.15.....5y=11.40-3.15=8.25...y=1.65\)
C
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