Answer:
three tenths of the original amount
Let's start.
There are 10 horses.
(Buying the set is not important, since it does not affect this scenario.)
You sell three horses to Kate, and you expect her to give you the exact price.
Let's say that 10 horses cost the total (unknown).
10 horses equal the total amount, or 1
10 to 1
Now, you sell 3 of these horses. You must multiply 10 and n to make 3.
10 x n = 3
10x 3/10 = 3
Do the same to the other side.
1 x 3/10 = 3/10
3 to 3/10
