Help!!!

[2(8-7)-[7-(-6-7)]  =

2(1) - [7 - (-13)] =

2 - [ 7 + 13] =

2 - 20 =

-18

CPhill: I think you made a small mistake by neglecting a -7 in the left bracket. I blieve the answer to be

-25. Thanks.

Simplify the following:
2 (8-7)-7-(7-(-6-7))
Group the negative terms in -6-7 together and factor out the minus sign.
-6-7 = -(6+7):
2 (8-7)-7-(7--(6+7))
Evaluate 6+7.
6+7 = 13:
2 (8-7)-7-(7-(-13))
Multiply all instances of -1 in -(-13).
(-1)^2 = 1:
2 (8-7)-7-(7+13)
Subtract 7 from 8.
8-7 = 1:
2×1-7-(7+13)
Evaluate 7+13 using long addition.
| 1 |
| 1 | 3
+ |  | 7
| 2 | 0:
2×1-7-20
Multiply 2 and 1 together.
2×1  =  2:
2-7-20
Group the negative terms in 2-7-20 together and factor out the minus sign.
2-7-20 = 2-(7+20):
2-(7+20)
Evaluate 7+20.
7+20 = 27:
2-27
Factor out a negative sign in 2-27 in order to subtract.
2-27  =  -(27-2):
-(27-2)
Subtract 2 from 27.
| 2 | 7
- |  | 2
| 2 | 5:
Answer: | 
| -25