During a race a sprinter increases from 5.0 m/s to 7.5 m/s over a period of 1.25 s what is the sprinters average acceleration during this period

So keep in mind acceleration is velocity over time, or more specifically, Δvelocity / Δtime. You're given a change in velocity and time. So your equation should look like: 


Solve that equation, and remember acceleration will be in !

Look it up you feel me