Please help, thank you!

a. What is Green Rider's break-even point in units and sales dollars? b. If the company has an after-tax income goal of $1 billion and the tax rate is 50 percent, how many units of each type of scooter must be sold for the c. Assume the sales mix shifts to 50 percent Mod, 40 percent Rad, and 10 percent X-treme. How does this change affect your answer to (a)? Note: Do not round until you determine the number of units of each product; round number of units to the next highest whole unit in your calculations