Idon't get it, can someone explain !

The mean of a set of data is -3.82 and its standard deviation is 2.31. find the z score for a value of 3.99.

Ineed big ! the cost of a school banquet is $25 plus $15 for each person attending. create a table, sketch the graph, and write an equation in slope-intercept and point-slope form that gives total cost as a function of the number of people attending. what is the cost for 77 people?

Which linear inequality is represented by the graph?