Whitch of the answer choices are equations ? select all that apply.

Aman steps out of a plane at a height of 4,000m above the ground falls 2,000m very quickly and then opens his parachute and slowly falls the remaining 2000m to the ground what height above the ground would be the best choice for a reference point

Which ordered pair (c,d) is a solution to the given system of linear equations- c+2d=13 -9c-4d=-15

Given the equation f(x)=a(b)x where the initial value is 40 and the growth rate is 20% what is f(4)