1. 49.5*10又3/5-(50-1/2)*3/5
=49.5*(10+3/5)-49.5-3/5
=49.5*(10+3/5-3/5)
=49.5*10
=495
2. (1/15+2/17)*15*17
=1/15*15*17+2/17*15*17
=17+30
=47
1. 49.5*10又3/5-(50-1/2)*3/5
=49.5*(10+3/5)-49.5-3/5
=49.5*(10+3/5-3/5)
=49.5*10
=495
2. (1/15+2/17)*15*17
=1/15*15*17+2/17*15*17
=17+30
=47