If an item that originally cost $19 is increased to $21, what is the percentage of increase in the item?

10.53%

Step-by-step explanation:

Percentage change can be found using the formula ...

percent change = ((new value) - (old value)) / (old value) * 100%

For your numbers, this is ...

percent change = (($21 - $19) / $19) * 100% = 2/19*100% ≈ 10.53%

The increase is about 10.53%.