Answer
$x=-\frac{c}{a+b}$
Work Step by Step
We are trying to isolate $x$ in the equation $ax+bx=-c$
To do this, first, we must factor out the $x$ using the distributive property: $x(a+b)=-c$
Next, we divide by $a+b$ to isolate $x$: $\frac{-c}{a+b}=-\frac{c}{a+b}$
