I have 2 questions that I was required to tell if the language is regular or not. I have the answer so I know that the answer for both of them is true. But I don’t have the intuation why and I can’t think of how to build automate or equivalnce class. it seems that the states are inifinte.

- I have regular L, and I have L’:
`{x: there is y such that |y| = |x| and xy belongs to L}.`

why L’ is regular? - I have the language L2 which is all the words w such that for each sub-word u of w
`-10<= amount of a in v - amount of b in v < 10`

( the diff between amount of a and amount of be is at most 10). why L2 is regular