By the table, it seems to be that f = 1/2x
Assuming the first term in the first equation is actually x^2, then the ordered pair is C. (3, 3).
Answer:

Step-by-step explanation:
The inverse of a function is when the x and y are swapped. So the first step is to write f(x) as y and then swap the x and y
Original Equation:

write f(x) as y (since that's what it represents)

Swap x and y

Square both sides

Add 1 to both sides

So this gives you the equation:

A=P×(0.8)
A is the price after the markdown
P is the original price
0.8 is the multiplier because 1-(80/100)=0.8
80/100 is the same as 80%, which is the remaining value when 20% of the value of the item is deducted.