Answer
$s=3.5$
Work Step by Step
In order to solve this algebraic expression, we must isolate the variable. A variable is the letter in the problem (for instance, in the equation $2x=10$, $x$ is the variable).
Because multiplication and division are inverse operations (they cancel each other out), we know we must divide when a number is being multiplied by the variable and multiply when the variable is being divided by a number.
In the equation $5s=17.5$, we must get rid of the $5$, which the variable is being multiplied by, in order to solve. Thus, we divide both sides by $5$ to find that $$s=3.5.$$
We plug 3.5 in for s and confirm that our answer is, indeed, correct.