Pls help:( 1-4 it will mean a lot thank you!

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?

Two variables, x and y, vary inversely, and x=12 when y=4. what is the value of y when x=3?

The two square pyramids are similar. find the total volume of both pyramids if the ratio of their surface areas is 9/16