20．用递等式计算，写出必要的计算过程．能简便的要简便计算．
0 156656 156664 156670 156674 156680 156682 156686 156692 156694 156700 156706 156710 156712 156716 156722 156724 156730 156734 156736 156740 156742 156746 156748 156750 156751 156752 156754 156755 156756 156758 156760 156764 156766 156770 156772 156776 156782 156784 156790 156794 156796 156800 156806 156812 156814 156820 156824 156826 156832 156836 156842 156850 199269
| 25.6+28.44+11.56 | 6.4×（125×0.125） |
| 4.5÷0.25 | 25-5.2÷（0.9-0.64） |
| 3.86×1.3+0.14×1.3 | 0.49×[1÷（4.9-4.89）]+6 |
