Simply plug in:

Let us say that P = 100 $ and x = 10 %

Now if there are two successive discounts of 10 % and 20 % then the effective discount percentage will be -10 - 20 + (-10) (-20)/100 = -30 + 2 = 28 %
Hence the new price will be 100 - 28 = 72

Hence by plugging in P = 100 and x = 10 the answer should be 72

A: P(1 - 0.03x + 0.02x^2) = 100 (1 - 0.3 + 2) = 100(2.7)
B: P(1 - 0.03x + 0.0002x^2) = 100 (1 - 0.3 + 0.02) = 100 (1 - 0.28) = 72 (BINGO!) (Lets still eliminate all other answer options - what if another one gives me 72)
C: P(1 - 0.03x + 0.002x^2) = 100 (1 - 0.3 + 0.2)
D: P(1 - 2x^2) = 100 ( 1 - 200)
E: P(1 - 3x + 2x^2) = 100 ( 1 - 0.2 + 200)

Hence the answer is B