Mathematics problem of grade one in junior high school: the process of 1 / 60 △ (1 / 4-1 / 5 + 1 / 3)

Mathematics problem of grade one in junior high school: the process of 1 / 60 △ (1 / 4-1 / 5 + 1 / 3)

1/60÷(15/60-12/60+20/60)
=60÷23/60
=60*60/23
=3600/23
Note: Division has no distributive law