12 timestvb now,tvbnow,bttvb/ V" l; F" J! y) m
tvb now,tvbnow,bttvb. o8 U* l9 \* Q# v$ E4 \/ q) R
each time 4 person but 1 need to back to pick up the other 3tvb now,tvbnow,bttvb$ ^, Q+ v$ i; |, h
return x 10 = 30 people6 O \( N4 ] h6 X1 {. D8 l4 A
1 time return
/ [: c, ^ P h( g; |1 w9 ^9 p; ^2 person on last time tvb now,tvbnow,bttvb3 y$ K) H0 x2 w
total : 12 times |