A beautiful and very successful actress（女演员）was the star for a new musical show.怎样算的?

A beautiful and very successful actress（女演员）was the star for a new musical show.怎样算的?
A beautiful and very successful actress（女演员）was the star for a new musical show.
Her home was in the countryside,but she did not want to go back there every
night,so she bought an expensive house in the centre of the city,got some
beautiful furniture and got a man to paint the rooms in new colours.
It was
very difficult to get tickets for her show,because everybody wanted to see it.
So she decided to give the painter two of the best seats.She hoped that this
would make him work better for her.He took the tickets without saying anything,
and she heard no more about them until the end of the month,when she got the
painter’s bill（账单）.At the bottom(底部) of it were these words:“ Four hours
watching Miss Hall sing and dance :3 pounds,” with this note:“ After 5 p.m.,I
get 15 shillings（先令）an hour instead of 10 shillings.”
【小题4】It can be learned from the text that one pound is___________ shillings.
A．10
B．12
C．20
D．15