According to the equation, how many hours will it take for the driver to complete the entire trip?

Correct answer: A. 4

The question asks for the number of hours, `x`, it will take for the driver to complete the entire trip. When the trip is complete, the number of miles remaining, `y`, will be 0. We can substitute 0 for `y` in the given equation: `0 = 160 - 40x`. To solve for `x`, we first add `40x` to both sides of the equation to get `40x = 160`. Then, we divide both sides by 40: `x = 160 / 40`, which simplifies to `x = 4`. Therefore, it will take the driver 4 hours to complete the trip. B is incorrect because 40 is the number of miles the driver covers each hour (the rate), not the total time for the trip. C is incorrect because 120 is the number of miles remaining after 1 hour (160 - 40*1), not the total time. D is incorrect because 160 is the total length of the trip in miles (the initial value when x=0), not the number of hours it takes.