PEMDAS comes first. Instead of adding 9+2 first, they should've multiplied 2x3. The final answer would be 15.
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The simplified form of this polynomial is (n(20n + 1))/5
16/ 2.10 = 7.6 ounces per $1
20/ 3.15 = 6.3 ounces per $1
So which do you think?