The formula is correct but I do not see any of the other statements. so yes the formula is true.
If we divide 800/1000, we get .8 This means The price of $800 is only 80% of $1000. Furthermore, this also means that there was a decrease in price of 20%. The answer is C.
The last two easy transformations involve flipping functions upside down (flipping them around the x-axis), and mirroring them in the y-axis.
The first, flipping upside down, is found by taking the negative of the original function; that is, the rule for this transformation is –f (x).