Let us take the third equation of motion.....i.e. v²-u²=2aS . Here, v = final velocity, u = initial velocity, a= acceleration and S= distance coveredNow,v²-u²=2aS=> (v u)(v-u) = 2aS=> (v u) = 2aS/ (v-u)=> (v u) = 2aS/at ...........1 [ Since By formula of acceleration, a=(v-u)/t => at = (v-u)]Again, putting this in 1,=> (v u) = 2S/t .... (Since 'a' gets cancelled)=> (v u)t = 2S=> S = 1/2t (v u)