Here is a letter to a friend inviting him to a picnic. The sentences have got jumbled up. Rearrange the sentences to make the content coherent.

I. What do you think of the proposition ?

II. Our family proposes to go on a one-week trip to Shimla.

III. We will be happy to have you with us.

IV. If you agree, we shall make additional arrangements for you at Shimla.