1. The condition of this question is not clear and cannot be answered.

2. Solution: (a-b)+(b-c)=a-c=6. Then:

(c-b)？ -4(b-a)(c-a)

=(b-c)？ -4(a-b)(a-c)

=4? -4x2x6

= 16-48

= -32.

3. solution: let X=4m, then: y=5m, z=7m. (m is not 0).

(4x-3y+2z)/(5y-2z+x)

=( 16m- 15m+ 14m)/(25m- 14m+4m)

=( 15m)/( 15m)

= 1