|How to calculate (1 / 5) - (1 / 7) | + | (1 / 9) - (1 / 7) | + | (1 / 9) - (1 / 11)

|How to calculate (1 / 5) - (1 / 7) | + | (1 / 9) - (1 / 7) | + | (1 / 9) - (1 / 11)

simple form
=1/5-1/7+1/7-1/9+1/9-1/11
=1/5-1/11
=6/55