Answer:
Because the price did not stay the same when they discounted it by 10% percent before.
Explanation:
10% percent of 450 is 45 so Subtracting that from 450 would give you,405.
They deducted another 10% percent a week later 10 percent of 405 would be 40.5 so you would subtract that from 405 which would make it 364.5
If you took 20% off originally then 20% of 450 is 90 so subtracting that would make 450 into 360 which is different from 364.5