This is only broken up into two main parts: the "a" and the "b" of the equation.
The "a" is the y-coordinate when x is at 0 and the y-coordinate is 8 there so that fills it in.
The "b" is the rate at which for every time x increases by 1, the y decreases by a portion of its current. In this case, every time the x increases by one, the y value cuts in half which means the rate is .5 or one half.
