Can someone please show me how to do this question?

I know you have to antidifferentiate twice to get the displacement function but am i not sure exactly what to integrate.

A body moves in a straight line with an acceleration of $\displaystyle 10 m/s^2$

If after 2 seconds it passes through O and after 3 seconds is 25 metres from O, find its initial displacement relative to O.

Do I start off with $\displaystyle a=10t$ ?

Thanks, help is appreciated