Help me out three math problems of grade one in junior high school, about folding a corner on a piece of paper and finding the degree of one of the corners, which is similar to this one

Help me out three math problems of grade one in junior high school, about folding a corner on a piece of paper and finding the degree of one of the corners, which is similar to this one

If you fold a rectangular piece of paper in half, the more times you fold it, the more the number of creases. For example, after the first fold, there is one crease. After the second fold, there are three creases. (1) how many creases are there after the third fold? What about the fourth fold? (2) please find out the corresponding law between the number of creases and the number of folds