用递等式计算①987+104×65-1747②86.4÷3.2-6.4×3.2③3763÷7+17×2663④17-16.8÷（1.8+7.2×112）⑤（79+421-37）×6.3⑥1

Question

用递等式计算
①987+104×65-1747                   
②86.4÷3.2-6.4×3.2
③(37)/(63)÷7+(1)/(7)×(26)/(63)                    
④17-16.8÷（1.8+7.2×(1)/(12)）
⑤（(7)/(9)+(4)/(21)-(3)/(7)）×6.3                   
⑥15÷〔（(5)/(7)-(1)/(2)）÷(3)/(28)〕-0.5．

Answer 1

①987+104×65-1747 
=987+6760-1747
=7747-1747
=6000；
            
②86.4÷3.2-6.4×3.2
=27-20.48
=6.52；

③(37)/(63)÷7+(1)/(7)×(26)/(63)   
=(37)/(63)×(1)/(7)+(1)/(7)×(26)/(63)     
=（(37)/(63)+(26)/(63)）×(1)/(7)
=1×(1)/(7)
=(1)/(7)；
       
④17-16.8÷（1.8+7.2×(1)/(12)）
=17-16.8÷（1.8+0.6）
=17-16.8÷1.2
=17-14
=3；

⑤（(7)/(9)+(4)/(21)-(3)/(7)）×6.3    
=(7)/(9)×6.3+(4)/(21)×6.3-(3)/(7)×6.3    
=4.9+1.2-2.7
=6.1-2.7
=3.4；
         
⑥15÷[（(5)/(7)-(1)/(2)）÷(3)/(28)]-0.5
=15÷[(3)/(14)÷(3)/(28)]-0.5
=15÷2-0.5
=7.5-0.5
=7．