Solution-
The original or cost price of the good = $21.00
Then, it is marked up 78.7%, i.e the price is 78.7% more than the initial price, which in this case is $21.
The new price is,

Then, 10% profit must be earned after selling the good. Hence, the list price must be 10% more of 37.527,
So, the selling or list price is

∴ $41.28 is the selling price of the good and this is how you got it.