D=S(T) you can change this equation to:
D/T=S(T) / T (were looking to isolate S or speed)
D/T=S
Now we have our equation. Here, you can plug in the numbers.
115m/26s=S
115/26 m/s=S
4.42307... m/s=S
Follow your teachers instructions on rounding or significant figures to get the answer that they want!