Evaluate 12-((6-4)+(8-15))-(4-(3+2)-(1-7))

$12 - ((6 - 4) + (8 - 15)) - (4 - (3 + 2) - (1 - 7))$

Remove parentheses.

$12 - (6 - 4 + 8 - 15) - (4 - (3 + 2) - (1 - 7))$

Simplify each term.

Subtract $4$ from $6$ .

$12 - (2 + 8 - 15) - (4 - (3 + 2) - (1 - 7))$

Add $2$ and $8$ .

$12 - (10 - 15) - (4 - (3 + 2) - (1 - 7))$

Subtract $15$ from $10$ .

$12 - - 5 - (4 - (3 + 2) - (1 - 7))$

Multiply $- 1$ by $- 5$ .

$12 + 5 - (4 - (3 + 2) - (1 - 7))$

Simplify each term.

Add $3$ and $2$ .

$12 + 5 - (4 - 1 \cdot 5 - (1 - 7))$

Multiply $- 1$ by $5$ .

$12 + 5 - (4 - 5 - (1 - 7))$

Subtract $7$ from $1$ .

$12 + 5 - (4 - 5 - - 6)$

Multiply $- 1$ by $- 6$ .

$12 + 5 - (4 - 5 + 6)$

Subtract $5$ from $4$ .

$12 + 5 - (- 1 + 6)$

Add $- 1$ and $6$ .

$12 + 5 - 1 \cdot 5$

Multiply $- 1$ by $5$ .

$12 + 5 - 5$

Simplify by adding and subtracting.

Add $12$ and $5$ .

$17 - 5$

Subtract $5$ from $17$ .

$12$