选择合理的方法计算下列各题．①517+1905÷15-629；②435-1.25-0.75+0.4；③4.75×25+5.25÷2.5；④（57-23）÷521×5．

Question

选择合理的方法计算下列各题．
①517+1905÷15-629；                 
②4(3)/(5)-1.25-0.75+0.4；
③4.75×(2)/(5)+5.25÷2.5；                  
④（(5)/(7)-(2)/(3)）÷(5)/(21)×5．

(3)/(5)-1.25-0.75+0.4；
③4.75×(2)/(5)+5.25÷2.5；                  
④（(5)/(7)-(2)/(3)）÷(5)/(21)×5．(3)/(5)3355
(2)/(5)+5.25÷2.5；                  
④（(5)/(7)-(2)/(3)）÷(5)/(21)×5．(2)/(5)2255
(5)/(7)-(2)/(3)）÷(5)/(21)×5．(5)/(7)5577(2)/(3)）÷(5)/(21)×5．(2)/(3)2233(5)/(21)×5．(5)/(21)552121

Answer 1

①517+1905÷15-629=517+127-629=644-629=15②435-1.25-0.75+0.4=4.6-1.25-0.75+0.4=（4.6+0.4）-（1.25+0.75）=5-2=3③4.75×25+5.25÷2.5=4.75×25+5.25÷52=4.75×25+5.25×25=（4.75+5.25）×25=10×25=4④（57-...