Answer:
b) 18 m/s is the correct answer.
Step-by-step explanation:
initial velocity(u) = 30m/s
acceleration(a) = -4m/s²
time(t) = 3 seconds
final velocity(v) = ?
using the formula,
a = (v-u)/t
or, -4 = (v-30)/3
or, -12 = v-30
or, v = -12+30
so, v = 18 m/s