Question 324659
{{{a_ave=(vf-vi)/(tf-ti)}}}

First convert mph to ft/s.
1 mile/hr*(5280 ft/mile)*(1 hr/3600 sec)=1.47 ft/s
65 mph=95.3 ft/s
{{{a_ave=(vf-vi)/(tf-ti)}}}
{{{a_ave=(95.3-0)/(4.61)}}}
{{{a_ave=21}}} ft/s^2