`***/`
`1a,(1/8-1/5+3/40):4/5=0:4/5=0`
`b,6/7+1/7*2/7+1/7*5/7=1/7(6/7+2/7)*5/7=1/7*8/7*5/7=40/343`
`c,(0,75-1/4):5/6=(3/4-1/4):5/6=1/2*6/5=3/5`
`2a,2/3+x=-45%`
`<=>2/3+x=-9/20`
`<=>x=-67/60`
`b,2/9-7/8x=1/3`
`<=>7/8x=-1/9`
`<=>x=-8/63`
`c,x+0,3x=-1,3`
`<=>1,3x=-1,3`
`<=>x=-1`
`4,` Ta có: `14/27=(2*7)/(3*9)=2/3:9/7`
Hay: `14/27=(7*2)/(9*3)=7/2:3/9`