$220
The employee has to mark up the $100 piece of jewelry by 120%. This means that the employee must add 120% of 100 to the original price of the jewelery. To find this, we simply multiply, since "of" in math means multiplication.
So, we must calculate 120% • 100 = 120 (because 120% = 1.2 and 1.2 • 100 = 120)
Now, we just add: 100 + 120 = 220, so the selling price should be 220
