Initially the price of natural gas is 10 per 1000 cubic feet

Explanation:

Algebraically it is represented as follows:

$10/1000ft³

and the cost per 1 cubic feet:

$ 0.01/ft³

the invasive species was introduced due to commercial purpouses, as there was a demand for fur clothes and hence, a business opportunity connected to this product. actually, it was when the nutrias scaped, causing harm to the us ecosystems when they acquired the status of invasive species. in this case they have caused an environmental problem, but it could have affected also economic interests or even human health.