1. 7(b-2d)
2.13(2b-c+3)
3.y(b-1)
4.5x(y-7z)
5. (2a+3b)(m+n)
6. x(a-b)+y(a-b)=(x+y)(a-b)
7.3(a-4b)
8. 11(3x-y+2)
9. c(в-1)
10. 3a(b-5c)
11. (x+y)d(3-4)
12. (x+y)(a-c)
x^2-7x+1=0