Answer:
20% profit margin!
Explanation:
Let suppose If the cost of a bucket is $100.
As the bucket is sold to 1/5 of the bucket cost.
i.e. 1/5 × 100 = $20
We know that 20% of 100 is 20.
i.e. 20/100 × 100 = 20
It mathematically means if the cost of the bucket was 100, and he sold at a profit equal to one - fifth of its cost price. It indicates that he earned a $20 profit. In other words, the person got a 20% profit percentage.
Note: I tried to take sample costs like $100 to make you understand as simple as I can.
Thus, if a bucket is sold at a profit equal to one - fifth of its cost price, the profit margin will always 20%, because if there are 5 parts of an object, 1 part makes the 20%.
I hope you get my point.