3(-9+16)-6(-9)=

Solution for 3(-9+16)-6(-9)= equation:

3(-9+16)-6(-9)=0

We simplify the equation to the form, which is simple to understand 
3(-9+16)-6(-9)=0

Simplifying terms in parentheses
3*(+7)-6*(-9)=0

Reorder the terms in parentheses
+(+21)-6*(-9)=0

Remove unnecessary parentheses
+21-6+*(-9+)=0

Reorder the terms in parentheses
+21+(+54)=0

Remove unnecessary parentheses
+21+54=0

We move all terms containing  to the left and all other terms to the right. 
0=0-21-54

We simplify left and right side of the equation. 
0=-75

0=-75

The left and right sides are not equal, therefore there is no solution. This equation is invalid.