When asked about the mathematical formula, 5 out of 7-5 out of 7 + 8 out of 17 + 9 out of 17

When asked about the mathematical formula, 5 out of 7-5 out of 7 + 8 out of 17 + 9 out of 17

5 / 7-5 / 7 + 8 / 17 + 9 / 17
=0 + 8 / 17 + 9 / 17
=1