Use your kinematic equations. Start by writing what you know (initial velocity is 0, time is 0.3 seconds, and distance traveled can be measured from the drawing).
Once you know three things, you can use your kinematic equations to solve for the other two (details here: https://www.aplusphysics.com/courses/regents/videos/KinEqns_Reg/KinEqns_Reg.html)