几道数学解方程和简便运算
1.0.8:x=4/3 :0.2
2.(1/4 x+0.33)÷1/5=19.5
3.2.5×0.875+0.25×1.25
4.9998/9+998/9+98/9+1/3
5.2.5-5/12-1/6÷2/7