73 = 87 - n what is n

The parabola x = y² - 9 opens: a.)up b.)down c.) right d.)left

What are the domain and range of the function f(x)=2^x+1

Abicycle training wheel has a radius of 3 inches. the bicycle wheel has a radius of 10 inches.approximately how much smaller, in square inches and rounded to the nearest hundredth, is the area of the training wheel than the area of the regular wheel? *