A1200kg car moving at 25m/s has the brakes applied with a deceeration of 8.0m/s^2. how far does the car travel before it stops?

V=vnaut+at 0(want it to stop)=25+-8t(negative accel cuz its deceling)
-25/-8=t t=3.125 seconds or with sig figs 3.1 seconds
x=xnaut+vnaut*time+1/2*a*time^2
x(where it ends up)=0(we start distance from when it started to brake)+25*3.1+1/2*-8*3.1^2=39.06 meters or 39.1 meters 
x=0+25*3.1-.5*8*3.1^2 is the same equation as above with nothing written in. Are you in physics ap or reg? either way friend me lol(just joined website tonight)

What formula  this one  (x_/