Air pressure at sea level is 30 inches of mercury. At an altitude of h feet above the, air pressure, P, in inches of mercury, is given by,

Question

P =30e^(-3.23x10-5h)
a)Find th equation of the tangent line at h=0.
b)A rule of thumb is given by travelers is that air pressure drops about 1 inch for every 1000-foot increase in height above sea level. Write a formula for the air pressure given by this rule of thumb

c)what is the relation between your answer to part (a) (b).explain why the rule of thumb works
d)are the predictions made by the rule of thumb too large or too small?why?

please help me.....i can not solve it..i need these answer within 2 hours..please help me..