Question

Natalie accelerator skateboard along a straight path for 4 milliseconds to 0 milliseconds in 25.0 seconds find the acceleration.

Answer 1

m/s is meters per second not milliseconds :)
m/s^2 is the accelaration in m/s per second
v=v2-v1=0-4=-4
a=v/t
a=-4/25 m/s^2=-0.16 m/s^2