16.39-（6.39+2又十分之七）-7.3
=16.39-6.39-2.7-7.3
=10-10
=0
47.1x9.4-47.1÷5/2+47.1
=47.1x9.4-47.1x0.4+47.1
=47.1x(9.4-0.4+1)
=47.1x10
=471