How do you do the equation a2 + ab + ac + bc ?

You are at a restaurant and owe $38 for your meal. you want to leave a 20% tip. how much will your tip be?

The tile along the edge of a triangular community pool needs to be replaced? ?

Aweekly newspaper charges $72 for each inch in length and one column width. what is the cost of an ad that runs 2 column inches long and 2 columns wide? its not 288