I am having trouble with Sensitivity, can someone help explain how to find B-2 and C? (I've solved A and B-1

We are evaluating a project that costs $644,000, has an eight-year life, and has no salvage value. Assume that depreciation is straight-line to zero over the life of the project. Sales are projected at 70,000 units per year. Price per unit is $37, variable cost per unit is $21, and fixed costs are $725,000 per year. The tax rate is 35 percent, and we require a 15 percent return on this project.

a.	Calculate the accounting break-even point.(Do not round intermediate calculations and round your final answer to nearest whole number. (e.g., 32))

Break-even point

50343.75units

b-1	Calculate the base-case cash flow and NPV.(Do not round intermediate calculations and round your NPV answers to 2 decimal places. (e.g., 32.16))

Cash flow	$2,84,925
NPV	$6,34,550

b-2	What is the sensitivity of NPV to changes in the sales figure?(Do not round intermediate calculations and round your final answer to 3 decimal places. (e.g., 32.161))

NPV / Q

$

c.	What is the sensitivity of OCF to changes in the variable cost figure?(Do not round intermediate calculations. Negative amount should be indicated by a minus sign.)

OCF / VC

$