Answer:
100 m. 
Explanation:
The following data were obtained from the question:
Initial velocity (u) = 10 m/s
Final velocity (v) = 30 m/s
Acceleration (a) = 4 m/s²
Displacement (D) =? 
Next, we shall determine the time.
This can be obtained as follow:
Acceleration is defined as the rate of change of velocity with time. Mathematically, it is expressed as:
a = (v – u) / t
Where 
a is the acceleration. 
u is the initial velocity. 
v is the final velocity. 
t is the time. 
With the above formula, we can obtain the time as follow:
Initial velocity (u) = 10 m/s
Final velocity (v) = 30 m/s
Acceleration (a) = 4 m/s²
Time (t) =? 
a = (v – u) / t
4 = (30 – 10)/t
4 = 20/t
Cross multiply 
4 × t = 20
Divide both side by 4
t = 20/4
t = 5 secs. 
Finally, we shall calculate the displacement of car as illustrated below:
Velocity is defined as rate of change of displacement with time. Mathematically, it can be expressed as:
(v – u) = D/ t
Where:
u is the initial velocity. 
v is the final velocity. 
t is the time. 
D is the displacement. 
With the above formula, we can calculate the displacement of the car as follow:
Initial velocity (u) = 10 m/s
Final velocity (v) = 30 m/s
Time (t) = 5 s.
Displacement (D) =?
(v – u) = D/ t
(30 – 10) = D/5
20 = D/5
Cross multiply 
D = 20 × 5
D = 100 m
Therefore, the displacement of the car is 100 m