Please help how to solve the problem

Julie James is opening a lemonade stand. She believes the fixed cost per week of running the stand is $200. Her best guess is that she can sell 1000 cups per week at $.80 per cup. The variable cost of producing a cup of lemonade is $.30? a) given her other assumptions, what level of sales volume will enable Julie to break even using goal seek function b) given her other assumptions, discuss how a change in sales and variable cost jointly affect profit using the two-way data table