解方程：
9÷ 3/4 χ = 1/3
3/4x=9÷1/3
3/4x=27
x=36
χ－3/5 χ= 6/5
2/5x=6/5
x=6/5÷2/5
x=3
1－25%χ=0.5
25%x=1-0.5
25%x=0.5
x=2