Nine-tenths (9/10) of a foot of rain would be collected in one day.
Answer:

In order to maximize the last equation we can derivate the function in term of x and we got:

And setting this derivate equal to 0 we got:

And solving for x we got:

And for this case the value that maximize the profit would be x =95 and the corresponding profit would be:

Step-by-step explanation:
For this case we have the following function for the profit:

And we can rewrite this expression like this:

In order to maximize the last equation we can derivate the function in term of x and we got:

And setting this derivate equal to 0 we got:

And solving for x we got:

And for this case the value that maximize the profit would be x =95 and the corresponding profit would be:

Domain of 5x^2 + 2x - 1 is all real numbers.
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