:(0.4x-0.9)/0.5-(0.3x+0.2)/0.3=(x-5)/2
:(4x-9)/5-(3x+2)/3=(x-5)/2
6(4x-9)-10(3x+2)=15(x-5)
24x-54-30x-20=15x-75
24x-30x-15x=-75+54+20
-21x=-1
x=1/21