3 kilometres = how many millimetres

If f(x)=2x-6 and g(x)=3x+9, find (f-g)(x)

The difference of two numbers is 40. find the numbers if 0.3 parts of one number is equal to 37.5% of the other one.

An incoming airplane is x miles due north from the control tower at an airport. a second incoming airplane is y miles due east of the same control tower. the shortest distance between the two airplanes is z miles. which of the following functions would best model the situation above?