Each person should get 4 4/5. That will be between the numbers 4 and 5.
Using the given data you can build the linear regression (described by linear function y=ax+b) by hand or you can use math calculator to do this. In attached diagram you can see that

and

Then the equation of linear function is

Answer: correct choice is D.
25% — $40
100% — $40 * 4 = $160
The original price is $160.