How to solve -x^2-2x+1

Use sigma notation to represent the following series for 9 terms.

There are a total sales of 2,000 dollars on monday on tuesday sales dropped 10% on wednesday sales dropped another 20% compared with tuesday from wednesday to thursday sales increases by an equal amount to 25% of monday total sales what is the net change in dollars on total sales from monday to tuesday

If f(x) = 5х – 2 and g(x) = 2х + 1, find (f – g)(x).