用递等式计算．①6.75+117÷3.6-0.35②（6+10.88÷3.2）×1.5③21.5÷[（6.07+2.53）×0.5]④0.5×[1÷（7.1-7.09）+6.4]．

Question

用递等式计算．
①6.75+117÷3.6-0.35           
②（6+10.88÷3.2）×1.5
③21.5÷[（6.07+2.53）×0.5]
④0.5×[1÷（7.1-7.09）+6.4]．

Answer 1

①6.75+117÷3.6-0.35
=6.75+32.5-0.35
=39.25-0.35
=38.9；

②（6+10.88÷3.2）×1.5
=（6+3.4）×1.5
=9.4×1.5
=14.1；

③21.5÷[（6.07+2.53）×0.5]
=21.5÷[8.6×0.5]
=21.5÷4.3
=5；

④0.5×[1÷（7.1-7.09）+6.4]
=0.5×[1÷0.01+6.4]
=0.5×[100+6.4]
=0.5×106.4
=53.2．