Abody moving with velocity of 20 m/s begins to accelerate at 3 m/s2 how far does the body move in 5 seconds

Speed at the beginning of the 5 sec . . . 20 m/s

In 5 sec, the body gains  (3 x 5) = 15 m/s of speed

Speed at the end of the 5 sec . . . (20 + 15) = 35 m/s

Average speed during the 5 sec . . . (1/2) (20 + 35) = 27.5 m/s

Moving for 5 sec at the average speed of 27.5 m/s,

         distance = (5 x 27.5) = 137.5 meters

It would stay the same