It takes 214 kJ of work to accelerate a car from 23.1 m/s to 29.3 m/s. What is the car's mass?

Solve the equation

(M/2)(V2^2 - V1^2) = 214,000 J
to obtain M. You know what the two velocities are (V1 and V2).

M will be in kg if V is in m/s.