A car advertisement states that a certain car that emily miller loves can accelerate from rest to 70 km/h in 7 seconds. Find the cars average acceleration

Kinematics equations are vital for this:

v_0 (initial velocity) v_f (final velocity) a (acceleration)

v_0=70 km/h v_f = 0 km/h (rest)

Kinematics equation is a = (v_f-v-0) / time

a = (0-70) / (7/3600) which means it decelerates at - 36000 km/h

This number is humongous; I would advise you to re-check the problem and see if the the time it takes is 7 hours rather than 7 seconds. Notice that I put the time as 7/3600 because it is 7 seconds which should be converted to hours.