Respuesta :

Answer:

V²=U² + 2as

Where V=Final Velocity

U=Initial Velocity

a=acceleration ( Deceleration in this case)

s=distance covered

10² = 30² + 2(a)(20)

100 = 900 + 40a

100 - 900 = 40a

-800=40a

a= -800/40

a= -20ms-².

Its negative because the car Decelerated.