vi = initial speed = 75 miles/hour =167.7 m/s
vf = final speed = 25 miles/hour = 55.9234 m/s
t = time = 2.5 seconds=
a = acceleration
[tex]a=\frac{vf-vi}{t}[/tex]Replacing with the values given:
[tex]a=\frac{55.9234-167.7}{2.5}[/tex]a = 44.74 m/s^2