Mrs. blake's bill at a restaurant was $42.75. she wants to leave the waiter an 18% tip. how much will she pay in all, including tip?

The quick way to do this is to multiply the bill by 1, mult. it again by 0.18, and then add the two results together.  

Better and faster:  Mult. the bill amount ($42.75) by 1.18:

1.18($42.75) = $50.45 (answer)