#### Answer

s=80

#### Work Step by Step

In order to solve for s, we first need to get all of the terms with an s in them on the same side of the equation. Then, we need to isolate s by getting all of the numbers that are on the same side of the equation as s on the other side of the equation. Thus, we obtain:
$s=40+.5s \\\\ .5s=40 \\\\ s=80$