3ab-2bc a=-4 b=6 c=-9

3(-4)(6)-2(6)(-9)
-12(6)-12(-9)
-72- -108
-180

2ac-12b

2(-4)(-9)-12(6)
-8(-9)-72
72-72
0

3b-4c/2b-(c-b)

3(6)-4(-9)/2(6)-(-9-6)

18-36/12-(-15)

18-36/12+15

-18/27

3ab-2bc a=-4 b=6 c=-9

3(-4)(6)-2(6)(-9)
-12(6)-12(-9)
-72- -108 = -72+108 = +36
-180

so the answer is 36?

3b-4c/2b-(c-b)

3(6)-4(-9)/2(6)-(-9-6)
= 18+(36/12)+15 = 18+3+15 = 36

how did you get that?

shouldn't it be 18+36+15

and why did u add 18+(36/12)

I use parentheses to keep from getting confused and what part goes with what part.

(3b)-(4c/2b)-(c-b) but if you used
(3b-4c/2b) - (c-b) of course you will get two different answers.

[3(6)]-[4(-9)/2(6)]-[(-9-6)]

= 18+[(36/12)]+15 = 18+3+15 = 36

how did u get 36 with 18+[(36/12)]+15?

shouldn;t it be 54/27

wait why did u put 18+(36/12)+15 = 18+3+15 = 36

why cant it be 18+36/12-3?

That last term is -(-9-6) = -(-15) = +15

When a - sign precedes a set of parentheses, the sign inside is changed.

So -(-9-6). Adding inside the parentheses gives -9-6 = -15 and -(-15) = +15