[9/10-3/7×(4/5-1/3)]/(9/10-3/5)
=[9/10-3/7×(12/15-5/12)]/(9/10-6/10)
=(9/10-3/7×7/12)/(3/10)
=(9/10-1/4)/(3/10)
=(18/20-5/20)/(3/10)
=13/20×10/3
=13/6
[9/10-3/7×(4/5-1/3)]/(9/10-3/5)
=[9/10-3/7×(12/15-5/12)]/(9/10-6/10)
=(9/10-3/7×7/12)/(3/10)
=(9/10-1/4)/(3/10)
=(18/20-5/20)/(3/10)
=13/20×10/3
=13/6