Work Step by Step
We are given $(12x-1.7)+(15x+6.2)=12x-1.7+15x+6.2=27x+7.9$. However, this last step is an incorrect combination of like terms. $12x-1.7+15x+6.2=(12x+15x)+(-1.7+6.2)=27x+4.5$
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