Answer
$b=\frac{10+a}{2}$
Work Step by Step
We are trying to isolate the b variable in $a-2b=-10$
To do this, we must first get the $b$ term on a side by itself by subtracting $a$ from each side to cancel out the $a$ that is added to the $b$ : $-2b=-10-a$
Then, we must divide by the $-2$ that is being multiplied by the $b$ to get it alone: $y=\frac{-10-a}{-2}$
Since all terms are negative in the fraction, we can rewrite it as $\frac{10+a}{2}$ by multiplying by $\frac{-1}{-1}$.
