While a man's mowing lawn, a man and a woman are helping him to clean up the backyard.
three people are in the backyard
The man mowing the lawn plus a man and woman helping makes three people in the backyard
exists e1 p1 x1 x2 x3 x4 x5 x6 x7.(n_backyard(x7) & while(e1,x5) & n_lawn(x5) & of(x5,x6) & n_mowing(x6) & of(x5,x4) & n_man(x4) & Topic(e1,p1) & Recipient(e1,x2) & Actor(e1,x1) & v_help(e1) & exists e2 s1.(a_up(s1) & Manner(e2,s1) & Theme(e2,x7) & Actor(e2,x2) & v_clean(e2)) & n_male(x2) & subset_of(x3,x1) & n_woman(x3) & subset_of(x2,x1) & n_man(x2))
exists p1 x1 x2.(n_backyard(x2) & in(x1,x2) & n_people(x1) & card_eq_3(x1))