Please help with 4 and 5!!

Miranda was reviewing the water bill for her dog day care and spa and determined that her highes bill,$5,000, occurred in July when she washed 500 dogs and her lowest bill, $3,600, occurred in Febru when she washed 325 dogs. What was the variable cost per dog associated with Miranda's water bill Dayton Company has fixed costs of $350,000. Total costs, both fixed and variable, are $450,000 40,000 units are produced. Calculate the total costs if the volume increases to 65,000 units. Round intermediate calculations to two decimal places, and your final answer to the nearest dollar. The dollar amount that provides for covering fixed costs and then provides for operation called