How to correct 5 out of 7-2 out of 15-12 out of 30

How to correct 5 out of 7-2 out of 15-12 out of 30

5 out of 7-2 out of 15-12 out of 30
=5 / 7 - (4 / 30 + 12 / 30)
=5 / 7-8 / 15
=75 / 105-56 / 105
=19 out of 105