Answer
given,
before collision
mass of car A = m_a = 1300 kg
velocity of car A = v_a = 35 mph
mass of car B = m_b= 1000 kg
velocity of car B = v_b = 25 mph
after collision
V_a = 30 mph
V_b = 31.5 mph
Initial momentum
[tex]P_1 = m_av_a + m_b v_b[/tex]
[tex]P_1 = 1300 \times 35+ 1000 \times 25[/tex]
[tex]P_1 =70500 Kg.m/s[/tex]
final momentum
[tex]P_2 = m_aV_a + m_b V_b[/tex]
[tex]P_2 = 1300 \times 30+ 1000 \times 31.5[/tex]
[tex]P_2 =70500 Kg.m/s[/tex]
here initial momentum is equal to the final momentum of the car.
hence, momentum is conserved in the collision.