(10 +20+24)/2. 27
>> (10 +20+24)/2 => 27
Nice, and here's the work...
dog + rabbit = 20g
cat + rabbit = 10g
cat + dog = 24g
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2dog + 2rabbit + 2cat = 54g
2(dog + rabbit + cat) = 54g
dog + rabbit + cat = 27g