Thank you for posting your question here at brainly. I hope the answer will help you. Below is the solution:
Make a momentum balance:
m_e · v_e + m_n · v_n = (m_e + m_n) · v
where v is the speed of the two cars instant after the collision.
Because the cars have the same mass, this simplifies to
v_e + v_n = 2v
The square of the speed instant after collision is:
v² = 1/4·(v_e + v_n)²
