https://www.chegg.com/homework-help/questions-and-answers/93-2-four-cargo-ships-used-shipping-goods-one-port-four-ports-labeled-1-2-3-4--ship-used-m-q35640300
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https://www.chegg.com/homework-help/questions-and-answers/1-compute-derivative-frac-d-y-d-x-3-x-sin-x-3-y-ln-left-frac-y-x-right-2-e--express-soluti-q103554026#question-transcript
https://www.chegg.com/homework-help/questions-and-answers/4-let-f-x-6-x-cos-pi-x--given-f-x-one-one-use-linear-approximation-f-1-around-5-estimate-f-q103554031