8．直接写出得数．
| $\frac{1}{5}$+$\frac{4}{5}$= | $\frac{5}{8}$-$\frac{1}{4}$= | $\frac{3}{7}$×$\frac{1}{3}$= | $\frac{1}{2}$÷60%= |
| 2-$\frac{3}{8}$= | 7÷70%= | 0.9+99×0.9= | $\frac{5}{9}$+$\frac{5}{9}$÷$\frac{5}{3}$= |
7．在4：15的前项加上8，后项必须加上（ ），比值才不变．
0 157727 157735 157741 157745 157751 157753 157757 157763 157765 157771 157777 157781 157783 157787 157793 157795 157801 157805 157807 157811 157813 157817 157819 157821 157822 157823 157825 157826 157827 157829 157831 157835 157837 157841 157843 157847 157853 157855 157861 157865 157867 157871 157877 157883 157885 157891 157895 157897 157903 157907 157913 157921 199269
| A． | 30 | B． | 8 | C． | 15 |