The marked price of a computer is D dollar. Its price decreased by 20% in January and later increased by 10% in February. What is the final price of the computer in D dollars?

Compute the price after the 20% decrease in January:
The price decreased by 20%, which means the new price is 100% - 20% = 80% of the original price.
80% of the original price is 0.8 × D = 0.8 D.

Compute the price after the 10% increase in February.
The price increased by 10%, which means the new price is 100% + 10% = 110% of the price after the January decrease.
110% of 0.8 D is 1.1 × 0.8D = 0.88 D.