-3(6+1)=123

Solution for -3(6+1)=123 equation:

-3(6+1)=123

We simplify the equation to the form, which is simple to understand 
-3(6+1)=123

Simplifying terms in parentheses
-3*(+7)=123

Reorder the terms in parentheses
+(-21)=123

Remove unnecessary parentheses
-21=+123

We move all terms containing  to the left and all other terms to the right. 
0=+123+21

We simplify left and right side of the equation. 
0=+144

0=144

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