Dose any one have a good site for finding the area of a polygon games

The table shows the webster family’s monthly expenses for the first three months of the year. they are $2,687.44, $2,613.09, and $2,808.64. what is the average monthly expenditure for all expenses?

Can someone me and do the problem plz so i can understand it more better

Suppose y varies directly with x. write a direct variation equation that relates x and y. then find the value of y when x=12 y=7 when x=3