can you show me step by step how you do did it?

Here's your original problem:

what is 1 and 8 twentieths subtracted by 15 twentieths.i get confused.do you have to borrow.

1 8/20

1 = 20/20

20/20 + 8/20 = 28/20

28/20 - 15/20 = 13/20