What is the reciprocal of 5/6

Can someone me with my hwplz(only the circled ones)

An energy plant is looking into putting in a system to remove harmful pollutants from its emissions going into earth's atmosphere. the cost of removing the pollutants can be modeled using the function c = 25000p/100 -p what is the vertical asymptote?

Estimate the area under the curve f(x) = 16 - x^2 from x = 0 to x = 3 by using three inscribed (under the curve) rectangles. answer to the nearest integer.