脱式计算 （能简算的要简算）．
72.8÷5.6+1.49       58.1﹣29.7÷3           30.94﹣5.09﹣4.91
3.94+34.3×0.2       5.4×2.3+5.4×7.7       3.2×12.5×0.25．