Super Bowl Puzzle Challenge

Arrange the digits 1 thru 9 in order from small to large,
inserting plus and minus signs to produce a total of 100.

1 2 3 4 5 6 7 8 9 so it equals 100

I know of two solutions.

After 40 years of teaching high school Mathematics I have decided to pass my solving skills and creative explanations to anyone in need!