Answer:
The percentage markdown is 15 % .
Explanation:
Formula

Where
Change in Price = Final price - Initial price
As given
A laptop was originally sold for $975.
The laptop is now on sale for $828.75.
Initial price = $975
Final price = $828.75
Change in Price = $828.75 - $975
= - $146.25
(As the negative sign represented the decrease thus negelected .)
= $146.25
Putting all the values in the formula



= 15%
Therefore the percentage markdown is 15 % .