im having trouble with b-2 and c

We are evaluating a project that costs $768,000, has a life of 6 years, and has no salvage value. Assume that depreciation is straight-line to zero over the life of the project. Sales are projected at 44,000 units per year. Price per unit is $60, variable cost per unit is $35, and fixed costs are $770,000 per year. The tax rate is 25 percent and we require a return of 13 percent on this project. a. Calculate the accounting break-even point. (Do not round intermediate calculations and round your answer to the nearest whole number, e.g., 32.) b-1. Calculate the base-case cash flow and NPV. (Do not round intermediate calculations and round your NPV answer to 2 decimal places, e.g., 32.16.) b-2. What is the sensitivity of NPV to changes in the sales figure? (Do not round intermediate calculations and round your answer to 3 decimal places, e.g., 32.161.) c. What is the sensitivity of OCF to changes in the variable cost figure? (A negative answer should be indicated by a minus sign. Do not round intermediate calculations and round your answer to the nearest whole number, e.g., 32.)