Evaluate ((4+2-11)+(13+9-20))-((-3+5-21)-(18-15+6))

$((4 + 2 - 11) + (13 + 9 - 20)) - ((- 3 + 5 - 21) - (18 - 15 + 6))$

Remove parentheses.

$4 + 2 - 11 + 13 + 9 - 20 - ((- 3 + 5 - 21) - (18 - 15 + 6))$

Simplify each term.

Subtract $15$ from $18$ .

$4 + 2 - 11 + 13 + 9 - 20 - (- 3 + 5 - 21 - (3 + 6))$

Add $3$ and $6$ .

$4 + 2 - 11 + 13 + 9 - 20 - (- 3 + 5 - 21 - 1 \cdot 9)$

Multiply $- 1$ by $9$ .

$4 + 2 - 11 + 13 + 9 - 20 - (- 3 + 5 - 21 - 9)$

Add $- 3$ and $5$ .

$4 + 2 - 11 + 13 + 9 - 20 - (2 - 21 - 9)$

Subtract $21$ from $2$ .

$4 + 2 - 11 + 13 + 9 - 20 - (- 19 - 9)$

Subtract $9$ from $- 19$ .

$4 + 2 - 11 + 13 + 9 - 20 - - 28$

Multiply $- 1$ by $- 28$ .

$4 + 2 - 11 + 13 + 9 - 20 + 28$

Simplify by adding and subtracting.

Add $4$ and $2$ .

$6 - 11 + 13 + 9 - 20 + 28$

Subtract $11$ from $6$ .

$- 5 + 13 + 9 - 20 + 28$

Add $- 5$ and $13$ .

$8 + 9 - 20 + 28$

Add $8$ and $9$ .

$17 - 20 + 28$

Subtract $20$ from $17$ .

$- 3 + 28$

Add $- 3$ and $28$ .

$25$