Answer:
20%
Explanation:
We were given a price at $50 on sale for $40. To get the markdown percentage, take the amount of money you've discounted the merchandise at and divide it by the sales price.
$50 sweaters, you can put them on sale for $40.

The difference between these two prices is $10.
Now, we need to add the amount of which it was marked down

Therefore, the watch has been marked down by 20%.