I was trying to figure it out but all i got was the meaning of the upside down U. so in the theory of a 9th grader i think...
you would have to distribute A' in to ( C U B)
because with the information i got it has to be in all so by distributing it would be in "all".
being a 9th grader i don't know if this helped but i hope it did just a little! and i deeply apologize if it doesn't.
