Set hamburgers x French fries y cola 9-X-Y

10X+4Y+3(9-X-Y)=52

10X+4Y+27-3X-3Y=52

7X+Y=25

Then let's analyze, if we only buy hamburgers, we must meet 7X+Y, so X≤3.

Similarly, y can only be equal to 18, 1 1, 4.

Similarly, 9-X-Y≤ 14

X+Y≥5

The above conditions are satisfied, so X=3 Y=4 9-X-Y=2.

Three hamburgers, four fries and two cokes.

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