A travel agency: a+a+0.5a = 2.5a.

Travel agency: (a+a+a) * 0.8 = 2.4a.

Because 2.5a >: 2.4a

So a charges more.

Height 2.5a-2.4a=0. 1a

If a=600

Then:

B =2.4*600= 1440 (yuan)

I wonder if I can see it clearly.