Calculating the New Price After a 10% Increase

To find the new price after a 10% increase, use the following formula:

[ \text{New Price} = \text{Original Price} + (\text{Original Price} \times \text{Percentage Increase}) ]

Substituting the given values, the new price = $20 + ($20 x 0.10) = $22.

Therefore, the new price of the shirt after a 10% increase is $22.