=(x-y)(x-2y)
1/(x-y)？ =(x-2y)/(x-y)？ (x-2y)
2/(x-y)(x-2y)=2(x-y)/(x-y)？ (x-2y)；
Original formula =a(x-2y)(x+2y)/(x+2)(x-2)
The original formula = (a+b+c) (a+b-c)/(a+b+c) = a+b-c.
Original formula =(3m-n)? /(3m-n)=3m-n
Original formula =2(a+b)/[4(a+b)(a-b)]
= 1/[2(a-b)]
Riddles are designed according to human cognitive characteristics, and people often need to solve them through metaphor and association. The following is what