數学題......come~~~

Q.1
Let original price = P
New selling price = P(1+20%) = 1.2P
Actual selling price after 20% discount = 1.2P(1-20%) = 1.2P x 0.8 = 0.96P.
Therefore, the change in selling price is -0.04P or (0.96P-P)/P = -0.04 = decrease 4%.
Q.2
Since the 2 numbers can be divided by 16.
Let one be 16x and the other is 16y.
So they can be 16 x 3 = 48 and 16 x 5 = 80. (80 is not a multiple of 48 because 5 is not a multiple of 3.)
Or 16x 2 = 32 and 16 x 7 = 112.(7 is not a multiple of 2).