The answer is:
B. 5.4 < 5.71
For this problem, let's use POE, or process of elimination.
Choice A is incorrect because 5.4 and 5.04 are 2 different things. Notice how "5.04" has a 0 before the 4, whilst "5.4" does not. There are not the same.
Choice B is correct because 5.4 (can also be read as 5.40) is less than 5.71. It is lower on the number line than 5.71.
Choice C is incorrect because 5.04 is not greater than 5.26. Think of it this way, you are saying: four is greater than twenty-six. That is not true.
Choice D is incorrect because 5.26 is not greater than 5.40. That is saying in words: twenty-six is greater than forty. It is not.
And voila, by POE, choice B is correct.
