An item is regularly priced at $40. Chau bought it at a discount of 45% off the regular price. How much did Chau pay?
The amount of discount is $40 x 45/100 = $<<40*45/100=18>>18.
So, Chau paid $40 - $18 = $<<40-18=22>>22. Answer: \boxed{22}.
So, Chau paid $40 - $18 = $<<40-18=22>>22. Answer: \boxed{22}.