Three men sit, and one man stands, on the back of a vehicle.
There are four people in the back of a vehicle.
Three men and one man makes four people.
exists e2 e1 x1 x2 x3 x4.(n_back(x3) & on(e2,x3) & of(x3,x4) & n_vehicle(x4) & Actor(e2,x2) & v_stand(e2) & n_man(x2) & card_eq_1(x2) & Actor(e1,x1) & v_sit(e1) & n_man(x1) & card_eq_3(x1))
exists p1 x1 x2 x3.(n_back(x2) & in(p1,x2) & of(x2,x3) & n_vehicle(x3) & exists x4.((x1 = x4) & n_people(x4) & card_eq_4(x4)))