S 15 км,t = 0,3

It looks like you are providing distance (S) and time (t) values, likely for a physics or mathematics problem, possibly involving speed or velocity.

If S = 15 kilometers and t = 0.3 hours, you can calculate the speed (v) using the formula:

\[ v = \frac{S}{t} \]

Substituting the given values:

\[ v = \frac{15 \text{ km}}{0.3 \text{ hours}} \]

Calculating this gives:

\[ v = 50 \text{ km/h} \]

So, the speed is 50 kilometers per hour. If you need further assistance or if this needs to be contextualized within a larger problem, feel free to provide more details!