They are integers that follow one right after another. For example the set {1,2,3,4,5} represents consecutive numbers. Another example would be {9,10,11,12,13}
In general, if x is some integer, then x+1 is the next integer right after x, and x+2 is right after x+1 and so on. The list is {x, x+1, x+2, x+3, ...} representing any general set of consecutive numbers.
It’s d, looks like you got it already! With ratios, just pay attention to not only the numbers but order of the words as well, so you can be sure the ratio follows the problem.
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