數學題(Probability)#2 5分

Field trip 25 boys and 20 girls are going on a field trip in a 36-passenger bus and a van. The students are distributed at random between the vehicles, filling the bus first. Find the probability that
a) there no girls in the van
b) there are no boys in the van
c) there are equal numbers of boys and girls in the bus
d) there are both equal numbers of boys and girls in the bus and equal numbers of boys and girls in the van


ans.10a=0.0023 b=1.895*10^-4 c=0.1031 d=0
請解釋步驟,thanks