3.14X40X3十3.14X(40÷4)x2=3.14x120+3.14x20x2=3.14x(120+40)=3.14x160=502.4
3.14X40X3十3.14X(40÷4)x2=3.14×120+3.14×20=3.14×140=439.6请采纳,谢谢
原式=3.14×(120+20)=3.14×140=439.6.